Merge branch 'master' into next

* master: (34 commits)
  Remove texts which were added by mistake in 00386272
  Fix formatting which was broken in 00386272
  LockFile: create OutputStream only when needed
  Add a cgit interoperability test for LockFile
  Add TemporaryBuffer.toString(int limit)
  LockFile: create OutputStream only when needed
  Prepare 5.12.0-SNAPSHOT builds
  JGit v5.12.0.202105051250-m2
  Update jetty to 9.4.40.v20210413
  [releng] Update eclipse-jarsigner-plugin to 1.3.1
  Implement ours/theirs content conflict resolution
  ssh: ensure list is modifiable before using Iterator.remove().
  Update orbit to S20210406213021 and add 4.20-staging target
  Fix typo in test method name
  Allow file mode conflicts in virtual base commit on recursive merge.
  sshd: don't lock the known_hosts files on reading
  Allow info messages in UsernamePasswordCredentialsProvider
  ssh config: do environment variable replacement
  sshd: implement server-sig-algs SSH extension (client side)
  Upgrade ecj to 3.25.0
  ...

Change-Id: Ibc39a9c4e431d15b67ab4a307241f47a7f3740a9

6 files changed, 302 insertions, 134 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/CherryPickCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/CherryPickCommand.java
index 5d0154c6dc..7922f9e729 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/CherryPickCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/CherryPickCommand.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com> and others
+ * Copyright (C) 2010, 2021 Christian Halstrick <christian.halstrick@sap.com> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -13,6 +13,7 @@ import java.io.IOException;
 import java.text.MessageFormat;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 
 import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
 import org.eclipse.jgit.api.errors.GitAPIException;
@@ -35,9 +36,12 @@ import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Ref.Storage;
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeMessageFormatter;
 import org.eclipse.jgit.merge.MergeStrategy;
+import org.eclipse.jgit.merge.Merger;
 import org.eclipse.jgit.merge.ResolveMerger;
+import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.FileTreeIterator;
@@ -61,6 +65,8 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 
 	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
 
+	private ContentMergeStrategy contentStrategy;
+
 	private Integer mainlineParentNumber;
 
 	private boolean noCommit = false;
@@ -121,16 +127,30 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 				String cherryPickName = srcCommit.getId().abbreviate(7).name()
 						+ " " + srcCommit.getShortMessage(); //$NON-NLS-1$
 
-				ResolveMerger merger = (ResolveMerger) strategy.newMerger(repo);
-				merger.setWorkingTreeIterator(new FileTreeIterator(repo));
-				merger.setBase(srcParent.getTree());
-				merger.setCommitNames(new String[] { "BASE", ourName, //$NON-NLS-1$
-						cherryPickName });
-				if (merger.merge(newHead, srcCommit)) {
-					if (!merger.getModifiedFiles().isEmpty()) {
+				Merger merger = strategy.newMerger(repo);
+				merger.setProgressMonitor(monitor);
+				boolean noProblems;
+				Map<String, MergeFailureReason> failingPaths = null;
+				List<String> unmergedPaths = null;
+				if (merger instanceof ResolveMerger) {
+					ResolveMerger resolveMerger = (ResolveMerger) merger;
+					resolveMerger.setContentMergeStrategy(contentStrategy);
+					resolveMerger.setCommitNames(
+							new String[] { "BASE", ourName, cherryPickName }); //$NON-NLS-1$
+					resolveMerger
+							.setWorkingTreeIterator(new FileTreeIterator(repo));
+					resolveMerger.setBase(srcParent.getTree());
+					noProblems = merger.merge(newHead, srcCommit);
+					failingPaths = resolveMerger.getFailingPaths();
+					unmergedPaths = resolveMerger.getUnmergedPaths();
+					if (!resolveMerger.getModifiedFiles().isEmpty()) {
 						repo.fireEvent(new WorkingTreeModifiedEvent(
-								merger.getModifiedFiles(), null));
+								resolveMerger.getModifiedFiles(), null));
 					}
+				} else {
+					noProblems = merger.merge(newHead, srcCommit);
+				}
+				if (noProblems) {
 					if (AnyObjectId.isEqual(newHead.getTree().getId(),
 							merger.getResultTreeId())) {
 						continue;
@@ -153,24 +173,26 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 					}
 					cherryPickedRefs.add(src);
 				} else {
-					if (merger.failed()) {
-						return new CherryPickResult(merger.getFailingPaths());
+					if (failingPaths != null && !failingPaths.isEmpty()) {
+						return new CherryPickResult(failingPaths);
 					}
 
 					// there are merge conflicts
 
-					String message = new MergeMessageFormatter()
+					String message;
+					if (unmergedPaths != null) {
+						message = new MergeMessageFormatter()
 							.formatWithConflicts(srcCommit.getFullMessage(),
-									merger.getUnmergedPaths());
+										unmergedPaths);
+					} else {
+						message = srcCommit.getFullMessage();
+					}
 
 					if (!noCommit) {
 						repo.writeCherryPickHead(srcCommit.getId());
 					}
 					repo.writeMergeCommitMsg(message);
 
-					repo.fireEvent(new WorkingTreeModifiedEvent(
-							merger.getModifiedFiles(), null));
-
 					return CherryPickResult.CONFLICT;
 				}
 			}
@@ -291,6 +313,22 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 	}
 
 	/**
+	 * Sets the content merge strategy to use if the
+	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
+	 * "recursive".
+	 *
+	 * @param strategy
+	 *            the {@link ContentMergeStrategy} to be used
+	 * @return {@code this}
+	 * @since 5.12
+	 */
+	public CherryPickCommand setContentMergeStrategy(
+			ContentMergeStrategy strategy) {
+		this.contentStrategy = strategy;
+		return this;
+	}
+
+	/**
 	 * Set the (1-based) parent number to diff against
 	 *
 	 * @param mainlineParentNumber
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/CommitCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/CommitCommand.java
index 041276c0f8..37f1d482aa 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/CommitCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/CommitCommand.java
@@ -20,6 +20,7 @@ import java.util.LinkedList;
 import java.util.List;
 
 import org.eclipse.jgit.api.errors.AbortedByHookException;
+import org.eclipse.jgit.api.errors.CanceledException;
 import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
 import org.eclipse.jgit.api.errors.EmptyCommitException;
 import org.eclipse.jgit.api.errors.GitAPIException;
@@ -36,6 +37,8 @@ import org.eclipse.jgit.dircache.DirCacheBuildIterator;
 import org.eclipse.jgit.dircache.DirCacheBuilder;
 import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.dircache.DirCacheIterator;
+import org.eclipse.jgit.errors.IncorrectObjectTypeException;
+import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.UnmergedPathException;
 import org.eclipse.jgit.hooks.CommitMsgHook;
 import org.eclipse.jgit.hooks.Hooks;
@@ -67,6 +70,8 @@ import org.eclipse.jgit.treewalk.FileTreeIterator;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.TreeWalk.OperationType;
 import org.eclipse.jgit.util.ChangeIdUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * A class used to execute a {@code Commit} command. It has setters for all
@@ -78,6 +83,9 @@ import org.eclipse.jgit.util.ChangeIdUtil;
  *      >Git documentation about Commit</a>
  */
 public class CommitCommand extends GitCommand<RevCommit> {
+	private static final Logger log = LoggerFactory
+			.getLogger(CommitCommand.class);
+
 	private PersonIdent author;
 
 	private PersonIdent committer;
@@ -173,8 +181,7 @@ public class CommitCommand extends GitCommand<RevCommit> {
 
 			if (all && !repo.isBare()) {
 				try (Git git = new Git(repo)) {
-					git.add()
-							.addFilepattern(".") //$NON-NLS-1$
+					git.add().addFilepattern(".") //$NON-NLS-1$
 							.setUpdate(true).call();
 				} catch (NoFilepatternException e) {
 					// should really not happen
@@ -212,7 +219,7 @@ public class CommitCommand extends GitCommand<RevCommit> {
 						.setCommitMessage(message).call();
 			}
 
-			// lock the index
+			RevCommit revCommit;
 			DirCache index = repo.lockDirCache();
 			try (ObjectInserter odi = repo.newObjectInserter()) {
 				if (!only.isEmpty())
@@ -226,100 +233,37 @@ public class CommitCommand extends GitCommand<RevCommit> {
 				if (insertChangeId)
 					insertChangeId(indexTreeId);
 
-				// Check for empty commits
-				if (headId != null && !allowEmpty.booleanValue()) {
-					RevCommit headCommit = rw.parseCommit(headId);
-					headCommit.getTree();
-					if (indexTreeId.equals(headCommit.getTree())) {
-						throw new EmptyCommitException(
-								JGitText.get().emptyCommit);
-					}
-				}
+				checkIfEmpty(rw, headId, indexTreeId);
 
 				// Create a Commit object, populate it and write it
 				CommitBuilder commit = new CommitBuilder();
 				commit.setCommitter(committer);
 				commit.setAuthor(author);
 				commit.setMessage(message);
-
 				commit.setParentIds(parents);
 				commit.setTreeId(indexTreeId);
 
 				if (signCommit.booleanValue()) {
-					if (gpgSigner == null) {
-						throw new ServiceUnavailableException(
-								JGitText.get().signingServiceUnavailable);
-					}
-					if (gpgSigner instanceof GpgObjectSigner) {
-						((GpgObjectSigner) gpgSigner).signObject(commit,
-								signingKey, committer, credentialsProvider,
-								gpgConfig);
-					} else {
-						if (gpgConfig.getKeyFormat() != GpgFormat.OPENPGP) {
-							throw new UnsupportedSigningFormatException(JGitText
-									.get().onlyOpenPgpSupportedForSigning);
-						}
-						gpgSigner.sign(commit, signingKey, committer,
-								credentialsProvider);
-					}
+					sign(commit);
 				}
 
 				ObjectId commitId = odi.insert(commit);
 				odi.flush();
+				revCommit = rw.parseCommit(commitId);
 
-				RevCommit revCommit = rw.parseCommit(commitId);
-				RefUpdate ru = repo.updateRef(Constants.HEAD);
-				ru.setNewObjectId(commitId);
-				if (!useDefaultReflogMessage) {
-					ru.setRefLogMessage(reflogComment, false);
-				} else {
-					String prefix = amend ? "commit (amend): " //$NON-NLS-1$
-							: parents.isEmpty() ? "commit (initial): " //$NON-NLS-1$
-									: "commit: "; //$NON-NLS-1$
-					ru.setRefLogMessage(prefix + revCommit.getShortMessage(),
-							false);
-				}
-				if (headId != null)
-					ru.setExpectedOldObjectId(headId);
-				else
-					ru.setExpectedOldObjectId(ObjectId.zeroId());
-				Result rc = ru.forceUpdate();
-				switch (rc) {
-				case NEW:
-				case FORCED:
-				case FAST_FORWARD: {
-					setCallable(false);
-					if (state == RepositoryState.MERGING_RESOLVED
-							|| isMergeDuringRebase(state)) {
-						// Commit was successful. Now delete the files
-						// used for merge commits
-						repo.writeMergeCommitMsg(null);
-						repo.writeMergeHeads(null);
-					} else if (state == RepositoryState.CHERRY_PICKING_RESOLVED) {
-						repo.writeMergeCommitMsg(null);
-						repo.writeCherryPickHead(null);
-					} else if (state == RepositoryState.REVERTING_RESOLVED) {
-						repo.writeMergeCommitMsg(null);
-						repo.writeRevertHead(null);
-					}
-					Hooks.postCommit(repo,
-							hookOutRedirect.get(PostCommitHook.NAME),
-							hookErrRedirect.get(PostCommitHook.NAME)).call();
-
-					return revCommit;
-				}
-				case REJECTED:
-				case LOCK_FAILURE:
-					throw new ConcurrentRefUpdateException(
-							JGitText.get().couldNotLockHEAD, ru.getRef(), rc);
-				default:
-					throw new JGitInternalException(MessageFormat.format(
-							JGitText.get().updatingRefFailed, Constants.HEAD,
-							commitId.toString(), rc));
-				}
+				updateRef(state, headId, revCommit, commitId);
 			} finally {
 				index.unlock();
 			}
+			try {
+				Hooks.postCommit(repo, hookOutRedirect.get(PostCommitHook.NAME),
+						hookErrRedirect.get(PostCommitHook.NAME)).call();
+			} catch (Exception e) {
+				log.error(MessageFormat.format(
+						JGitText.get().postCommitHookFailed, e.getMessage()),
+						e);
+			}
+			return revCommit;
 		} catch (UnmergedPathException e) {
 			throw new UnmergedPathsException(e);
 		} catch (IOException e) {
@@ -328,6 +272,89 @@ public class CommitCommand extends GitCommand<RevCommit> {
 		}
 	}
 
+	private void checkIfEmpty(RevWalk rw, ObjectId headId, ObjectId indexTreeId)
+			throws EmptyCommitException, MissingObjectException,
+			IncorrectObjectTypeException, IOException {
+		if (headId != null && !allowEmpty.booleanValue()) {
+			RevCommit headCommit = rw.parseCommit(headId);
+			headCommit.getTree();
+			if (indexTreeId.equals(headCommit.getTree())) {
+				throw new EmptyCommitException(JGitText.get().emptyCommit);
+			}
+		}
+	}
+
+	private void sign(CommitBuilder commit) throws ServiceUnavailableException,
+			CanceledException, UnsupportedSigningFormatException {
+		if (gpgSigner == null) {
+			throw new ServiceUnavailableException(
+					JGitText.get().signingServiceUnavailable);
+		}
+		if (gpgSigner instanceof GpgObjectSigner) {
+			((GpgObjectSigner) gpgSigner).signObject(commit,
+					signingKey, committer, credentialsProvider,
+					gpgConfig);
+		} else {
+			if (gpgConfig.getKeyFormat() != GpgFormat.OPENPGP) {
+				throw new UnsupportedSigningFormatException(JGitText
+						.get().onlyOpenPgpSupportedForSigning);
+			}
+			gpgSigner.sign(commit, signingKey, committer,
+					credentialsProvider);
+		}
+	}
+
+	private void updateRef(RepositoryState state, ObjectId headId,
+			RevCommit revCommit, ObjectId commitId)
+			throws ConcurrentRefUpdateException, IOException {
+		RefUpdate ru = repo.updateRef(Constants.HEAD);
+		ru.setNewObjectId(commitId);
+		if (!useDefaultReflogMessage) {
+			ru.setRefLogMessage(reflogComment, false);
+		} else {
+			String prefix = amend ? "commit (amend): " //$NON-NLS-1$
+					: parents.isEmpty() ? "commit (initial): " //$NON-NLS-1$
+							: "commit: "; //$NON-NLS-1$
+			ru.setRefLogMessage(prefix + revCommit.getShortMessage(),
+					false);
+		}
+		if (headId != null) {
+			ru.setExpectedOldObjectId(headId);
+		} else {
+			ru.setExpectedOldObjectId(ObjectId.zeroId());
+		}
+		Result rc = ru.forceUpdate();
+		switch (rc) {
+		case NEW:
+		case FORCED:
+		case FAST_FORWARD: {
+			setCallable(false);
+			if (state == RepositoryState.MERGING_RESOLVED
+					|| isMergeDuringRebase(state)) {
+				// Commit was successful. Now delete the files
+				// used for merge commits
+				repo.writeMergeCommitMsg(null);
+				repo.writeMergeHeads(null);
+			} else if (state == RepositoryState.CHERRY_PICKING_RESOLVED) {
+				repo.writeMergeCommitMsg(null);
+				repo.writeCherryPickHead(null);
+			} else if (state == RepositoryState.REVERTING_RESOLVED) {
+				repo.writeMergeCommitMsg(null);
+				repo.writeRevertHead(null);
+			}
+			break;
+		}
+		case REJECTED:
+		case LOCK_FAILURE:
+			throw new ConcurrentRefUpdateException(
+					JGitText.get().couldNotLockHEAD, ru.getRef(), rc);
+		default:
+			throw new JGitInternalException(MessageFormat.format(
+					JGitText.get().updatingRefFailed, Constants.HEAD,
+					commitId.toString(), rc));
+		}
+	}
+
 	private void insertChangeId(ObjectId treeId) {
 		ObjectId firstParentId = null;
 		if (!parents.isEmpty())
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
index d88f4ec561..c611f915ae 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com>
- * Copyright (C) 2010-2014, Stefan Lay <stefan.lay@sap.com>
- * Copyright (C) 2016, Laurent Delaigue <laurent.delaigue@obeo.fr> and others
+ * Copyright (C) 2010, 2014, Stefan Lay <stefan.lay@sap.com>
+ * Copyright (C) 2016, 2021 Laurent Delaigue <laurent.delaigue@obeo.fr> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -45,6 +45,7 @@ import org.eclipse.jgit.lib.Ref.Storage;
 import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeConfig;
 import org.eclipse.jgit.merge.MergeMessageFormatter;
 import org.eclipse.jgit.merge.MergeStrategy;
@@ -71,6 +72,8 @@ public class MergeCommand extends GitCommand<MergeResult> {
 
 	private MergeStrategy mergeStrategy = MergeStrategy.RECURSIVE;
 
+	private ContentMergeStrategy contentStrategy;
+
 	private List<Ref> commits = new LinkedList<>();
 
 	private Boolean squash;
@@ -320,6 +323,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 				List<String> unmergedPaths = null;
 				if (merger instanceof ResolveMerger) {
 					ResolveMerger resolveMerger = (ResolveMerger) merger;
+					resolveMerger.setContentMergeStrategy(contentStrategy);
 					resolveMerger.setCommitNames(new String[] {
 							"BASE", "HEAD", ref.getName() }); //$NON-NLS-1$ //$NON-NLS-2$
 					resolveMerger.setWorkingTreeIterator(new FileTreeIterator(repo));
@@ -473,6 +477,22 @@ public class MergeCommand extends GitCommand<MergeResult> {
 	}
 
 	/**
+	 * Sets the content merge strategy to use if the
+	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
+	 * "recursive".
+	 *
+	 * @param strategy
+	 *            the {@link ContentMergeStrategy} to be used
+	 * @return {@code this}
+	 * @since 5.12
+	 */
+	public MergeCommand setContentMergeStrategy(ContentMergeStrategy strategy) {
+		checkCallable();
+		this.contentStrategy = strategy;
+		return this;
+	}
+
+	/**
 	 * Reference to a commit to be merged with the current head
 	 *
 	 * @param aCommit
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/PullCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/PullCommand.java
index 449250890c..281ecfd011 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/PullCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/PullCommand.java
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.com>
  * Copyright (C) 2010, Mathias Kinzler <mathias.kinzler@sap.com>
- * Copyright (C) 2016, Laurent Delaigue <laurent.delaigue@obeo.fr> and others
+ * Copyright (C) 2016, 2021 Laurent Delaigue <laurent.delaigue@obeo.fr> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -43,6 +43,7 @@ import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.RepositoryState;
 import org.eclipse.jgit.lib.SubmoduleConfig.FetchRecurseSubmodulesMode;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
@@ -69,6 +70,8 @@ public class PullCommand extends TransportCommand<PullCommand, PullResult> {
 
 	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
 
+	private ContentMergeStrategy contentStrategy;
+
 	private TagOpt tagOption;
 
 	private FastForwardMode fastForwardMode;
@@ -275,8 +278,7 @@ public class PullCommand extends TransportCommand<PullCommand, PullResult> {
 					JGitText.get().pullTaskName));
 
 		// we check the updates to see which of the updated branches
-		// corresponds
-		// to the remote branch name
+		// corresponds to the remote branch name
 		AnyObjectId commitToMerge;
 		if (isRemote) {
 			Ref r = null;
@@ -354,8 +356,11 @@ public class PullCommand extends TransportCommand<PullCommand, PullResult> {
 			}
 			RebaseCommand rebase = new RebaseCommand(repo);
 			RebaseResult rebaseRes = rebase.setUpstream(commitToMerge)
-					.setUpstreamName(upstreamName).setProgressMonitor(monitor)
-					.setOperation(Operation.BEGIN).setStrategy(strategy)
+					.setProgressMonitor(monitor)
+					.setUpstreamName(upstreamName)
+					.setOperation(Operation.BEGIN)
+					.setStrategy(strategy)
+					.setContentMergeStrategy(contentStrategy)
 					.setPreserveMerges(
 							pullRebaseMode == BranchRebaseMode.PRESERVE)
 					.call();
@@ -363,7 +368,9 @@ public class PullCommand extends TransportCommand<PullCommand, PullResult> {
 		} else {
 			MergeCommand merge = new MergeCommand(repo);
 			MergeResult mergeRes = merge.include(upstreamName, commitToMerge)
-					.setStrategy(strategy).setProgressMonitor(monitor)
+					.setProgressMonitor(monitor)
+					.setStrategy(strategy)
+					.setContentMergeStrategy(contentStrategy)
 					.setFastForward(getFastForwardMode()).call();
 			monitor.update(1);
 			result = new PullResult(fetchRes, remote, mergeRes);
@@ -442,6 +449,21 @@ public class PullCommand extends TransportCommand<PullCommand, PullResult> {
 	}
 
 	/**
+	 * Sets the content merge strategy to use if the
+	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
+	 * "recursive".
+	 *
+	 * @param strategy
+	 *            the {@link ContentMergeStrategy} to be used
+	 * @return {@code this}
+	 * @since 5.12
+	 */
+	public PullCommand setContentMergeStrategy(ContentMergeStrategy strategy) {
+		this.contentStrategy = strategy;
+		return this;
+	}
+
+	/**
 	 * Set the specification of annotated tag behavior during fetch
 	 *
 	 * @param tagOpt
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
index 836175dcea..a26ffc2e66 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2010, 2013 Mathias Kinzler <mathias.kinzler@sap.com>
- * Copyright (C) 2016, Laurent Delaigue <laurent.delaigue@obeo.fr> and others
+ * Copyright (C) 2016, 2021 Laurent Delaigue <laurent.delaigue@obeo.fr> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -65,6 +65,7 @@ import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevSort;
@@ -212,6 +213,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 
 	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
 
+	private ContentMergeStrategy contentStrategy;
+
 	private boolean preserveMerges = false;
 
 	/**
@@ -501,8 +504,11 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 			String ourCommitName = getOurCommitName();
 			try (Git git = new Git(repo)) {
 				CherryPickResult cherryPickResult = git.cherryPick()
-					.include(commitToPick).setOurCommitName(ourCommitName)
-					.setReflogPrefix(REFLOG_PREFIX).setStrategy(strategy)
+					.include(commitToPick)
+					.setOurCommitName(ourCommitName)
+					.setReflogPrefix(REFLOG_PREFIX)
+					.setStrategy(strategy)
+					.setContentMergeStrategy(contentStrategy)
 					.call();
 				switch (cherryPickResult.getStatus()) {
 				case FAILED:
@@ -556,7 +562,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 							.include(commitToPick)
 							.setOurCommitName(ourCommitName)
 							.setReflogPrefix(REFLOG_PREFIX)
-							.setStrategy(strategy);
+							.setStrategy(strategy)
+							.setContentMergeStrategy(contentStrategy);
 					if (isMerge) {
 						pickCommand.setMainlineParentNumber(1);
 						// We write a MERGE_HEAD and later commit explicitly
@@ -592,6 +599,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 					MergeCommand merge = git.merge()
 							.setFastForward(MergeCommand.FastForwardMode.NO_FF)
 							.setProgressMonitor(monitor)
+							.setStrategy(strategy)
+							.setContentMergeStrategy(contentStrategy)
 							.setCommit(false);
 					for (int i = 1; i < commitToPick.getParentCount(); i++)
 						merge.include(newParents.get(i));
@@ -1137,7 +1146,7 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 	}
 
 	private List<RevCommit> calculatePickList(RevCommit headCommit)
-			throws GitAPIException, NoHeadException, IOException {
+			throws IOException {
 		List<RevCommit> cherryPickList = new ArrayList<>();
 		try (RevWalk r = new RevWalk(repo)) {
 			r.sort(RevSort.TOPO_KEEP_BRANCH_TOGETHER, true);
@@ -1587,6 +1596,21 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 	}
 
 	/**
+	 * Sets the content merge strategy to use if the
+	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
+	 * "recursive".
+	 *
+	 * @param strategy
+	 *            the {@link ContentMergeStrategy} to be used
+	 * @return {@code this}
+	 * @since 5.12
+	 */
+	public RebaseCommand setContentMergeStrategy(ContentMergeStrategy strategy) {
+		this.contentStrategy = strategy;
+		return this;
+	}
+
+	/**
 	 * Whether to preserve merges during rebase
 	 *
 	 * @param preserve
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/StashApplyCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/StashApplyCommand.java
index 56b3992fcd..1004d3e50f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/StashApplyCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/StashApplyCommand.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012, 2017 GitHub Inc. and others
+ * Copyright (C) 2012, 2021 GitHub Inc. and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -38,7 +38,9 @@ import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.RepositoryState;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeStrategy;
+import org.eclipse.jgit.merge.Merger;
 import org.eclipse.jgit.merge.ResolveMerger;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevTree;
@@ -71,6 +73,8 @@ public class StashApplyCommand extends GitCommand<ObjectId> {
 
 	private MergeStrategy strategy = MergeStrategy.RECURSIVE;
 
+	private ContentMergeStrategy contentStrategy;
+
 	/**
 	 * Create command to apply the changes of a stashed commit
 	 *
@@ -166,16 +170,25 @@ public class StashApplyCommand extends GitCommand<ObjectId> {
 			if (restoreUntracked && stashCommit.getParentCount() == 3)
 				untrackedCommit = revWalk.parseCommit(stashCommit.getParent(2));
 
-			ResolveMerger merger = (ResolveMerger) strategy.newMerger(repo);
-			merger.setCommitNames(new String[] { "stashed HEAD", "HEAD", //$NON-NLS-1$ //$NON-NLS-2$
-					"stash" }); //$NON-NLS-1$
-			merger.setBase(stashHeadCommit);
-			merger.setWorkingTreeIterator(new FileTreeIterator(repo));
-			boolean mergeSucceeded = merger.merge(headCommit, stashCommit);
-			List<String> modifiedByMerge = merger.getModifiedFiles();
-			if (!modifiedByMerge.isEmpty()) {
-				repo.fireEvent(
-						new WorkingTreeModifiedEvent(modifiedByMerge, null));
+			Merger merger = strategy.newMerger(repo);
+			boolean mergeSucceeded;
+			if (merger instanceof ResolveMerger) {
+				ResolveMerger resolveMerger = (ResolveMerger) merger;
+				resolveMerger
+						.setCommitNames(new String[] { "stashed HEAD", "HEAD", //$NON-NLS-1$ //$NON-NLS-2$
+								"stash" }); //$NON-NLS-1$
+				resolveMerger.setBase(stashHeadCommit);
+				resolveMerger
+						.setWorkingTreeIterator(new FileTreeIterator(repo));
+				resolveMerger.setContentMergeStrategy(contentStrategy);
+				mergeSucceeded = resolveMerger.merge(headCommit, stashCommit);
+				List<String> modifiedByMerge = resolveMerger.getModifiedFiles();
+				if (!modifiedByMerge.isEmpty()) {
+					repo.fireEvent(new WorkingTreeModifiedEvent(modifiedByMerge,
+							null));
+				}
+			} else {
+				mergeSucceeded = merger.merge(headCommit, stashCommit);
 			}
 			if (mergeSucceeded) {
 				DirCache dc = repo.lockDirCache();
@@ -184,11 +197,14 @@ public class StashApplyCommand extends GitCommand<ObjectId> {
 				dco.setFailOnConflict(true);
 				dco.checkout(); // Ignoring failed deletes....
 				if (restoreIndex) {
-					ResolveMerger ixMerger = (ResolveMerger) strategy
-							.newMerger(repo, true);
-					ixMerger.setCommitNames(new String[] { "stashed HEAD", //$NON-NLS-1$
-							"HEAD", "stashed index" }); //$NON-NLS-1$//$NON-NLS-2$
-					ixMerger.setBase(stashHeadCommit);
+					Merger ixMerger = strategy.newMerger(repo, true);
+					if (ixMerger instanceof ResolveMerger) {
+						ResolveMerger resolveMerger = (ResolveMerger) ixMerger;
+						resolveMerger.setCommitNames(new String[] { "stashed HEAD", //$NON-NLS-1$
+								"HEAD", "stashed index" }); //$NON-NLS-1$//$NON-NLS-2$
+						resolveMerger.setBase(stashHeadCommit);
+						resolveMerger.setContentMergeStrategy(contentStrategy);
+					}
 					boolean ok = ixMerger.merge(headCommit, stashIndexCommit);
 					if (ok) {
 						resetIndex(revWalk
@@ -200,16 +216,20 @@ public class StashApplyCommand extends GitCommand<ObjectId> {
 				}
 
 				if (untrackedCommit != null) {
-					ResolveMerger untrackedMerger = (ResolveMerger) strategy
-							.newMerger(repo, true);
-					untrackedMerger.setCommitNames(new String[] {
-							"null", "HEAD", "untracked files" }); //$NON-NLS-1$//$NON-NLS-2$//$NON-NLS-3$
-					// There is no common base for HEAD & untracked files
-					// because the commit for untracked files has no parent. If
-					// we use stashHeadCommit as common base (as in the other
-					// merges) we potentially report conflicts for files
-					// which are not even member of untracked files commit
-					untrackedMerger.setBase(null);
+					Merger untrackedMerger = strategy.newMerger(repo, true);
+					if (untrackedMerger instanceof ResolveMerger) {
+						ResolveMerger resolveMerger = (ResolveMerger) untrackedMerger;
+						resolveMerger.setCommitNames(new String[] { "null", "HEAD", //$NON-NLS-1$//$NON-NLS-2$
+								"untracked files" }); //$NON-NLS-1$
+						// There is no common base for HEAD & untracked files
+						// because the commit for untracked files has no parent.
+						// If we use stashHeadCommit as common base (as in the
+						// other merges) we potentially report conflicts for
+						// files which are not even member of untracked files
+						// commit.
+						resolveMerger.setBase(null);
+						resolveMerger.setContentMergeStrategy(contentStrategy);
+					}
 					boolean ok = untrackedMerger.merge(headCommit,
 							untrackedCommit);
 					if (ok) {
@@ -279,6 +299,23 @@ public class StashApplyCommand extends GitCommand<ObjectId> {
 	}
 
 	/**
+	 * Sets the content merge strategy to use if the
+	 * {@link #setStrategy(MergeStrategy) merge strategy} is "resolve" or
+	 * "recursive".
+	 *
+	 * @param strategy
+	 *            the {@link ContentMergeStrategy} to be used
+	 * @return {@code this}
+	 * @since 5.12
+	 */
+	public StashApplyCommand setContentMergeStrategy(
+			ContentMergeStrategy strategy) {
+		checkCallable();
+		this.contentStrategy = strategy;
+		return this;
+	}
+
+	/**
 	 * Whether the command should restore untracked files
 	 *
 	 * @param applyUntracked