LFS: support merge/rebase/cherry-pick/diff/compare with LFS files

Respect merge=lfs and diff=lfs attributes where required to replace (in
memory) the content of LFS pointers with the actual blob content from
the LFS storage (and vice versa when staging/merging).

Does not implement general support for merge/diff attributes for any
other use case apart from LFS.

Change-Id: Ibad8875de1e0bee8fe3a1dffb1add93111534cae
Signed-off-by: Markus Duft <markus.duft@ssi-schaefer.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

8 files changed, 417 insertions, 11 deletions

diff --git a/org.eclipse.jgit.lfs/.settings/.api_filters b/org.eclipse.jgit.lfs/.settings/.api_filters
index 097fd20658..f4887e272b 100644
--- a/org.eclipse.jgit.lfs/.settings/.api_filters
+++ b/org.eclipse.jgit.lfs/.settings/.api_filters
@@ -1,5 +1,13 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <component id="org.eclipse.jgit.lfs" version="2">
+    <resource path="src/org/eclipse/jgit/lfs/CleanFilter.java" type="org.eclipse.jgit.lfs.CleanFilter">
+        <filter id="421572723">
+            <message_arguments>
+                <message_argument value="org.eclipse.jgit.lfs.CleanFilter"/>
+                <message_argument value="register()"/>
+            </message_arguments>
+        </filter>
+    </resource>
     <resource path="src/org/eclipse/jgit/lfs/LfsPointer.java" type="org.eclipse.jgit.lfs.LfsPointer">
         <filter id="336658481">
             <message_arguments>
@@ -8,4 +16,12 @@
             </message_arguments>
         </filter>
     </resource>
+    <resource path="src/org/eclipse/jgit/lfs/SmudgeFilter.java" type="org.eclipse.jgit.lfs.SmudgeFilter">
+        <filter id="421572723">
+            <message_arguments>
+                <message_argument value="org.eclipse.jgit.lfs.SmudgeFilter"/>
+                <message_argument value="register()"/>
+            </message_arguments>
+        </filter>
+    </resource>
 </component>
diff --git a/org.eclipse.jgit.lfs/META-INF/MANIFEST.MF b/org.eclipse.jgit.lfs/META-INF/MANIFEST.MF
index 798fccdfc4..6d94877148 100644
--- a/org.eclipse.jgit.lfs/META-INF/MANIFEST.MF
+++ b/org.eclipse.jgit.lfs/META-INF/MANIFEST.MF
@@ -18,6 +18,7 @@ Import-Package: com.google.gson;version="[2.8.2,3.0.0)",
  org.eclipse.jgit.annotations;version="[4.11.0,4.12.0)";resolution:=optional,
  org.eclipse.jgit.api.errors;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.attributes;version="[4.11.0,4.12.0)",
+ org.eclipse.jgit.diff;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.errors;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.hooks;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.internal.storage.file;version="[4.11.0,4.12.0)",
@@ -25,6 +26,7 @@ Import-Package: com.google.gson;version="[2.8.2,3.0.0)",
  org.eclipse.jgit.nls;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.revwalk;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.storage.file;version="[4.11.0,4.12.0)",
+ org.eclipse.jgit.storage.pack;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.transport;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.transport.http;version="[4.11.0,4.12.0)",
  org.eclipse.jgit.treewalk;version="[4.11.0,4.12.0)",
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/BuiltinLFS.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/BuiltinLFS.java
new file mode 100644
index 0000000000..e1b9e34ed5
--- /dev/null
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/BuiltinLFS.java
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2017, Markus Duft <markus.duft@ssi-schaefer.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.lfs;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PrintStream;
+
+import org.eclipse.jgit.annotations.Nullable;
+import org.eclipse.jgit.attributes.Attribute;
+import org.eclipse.jgit.hooks.PrePushHook;
+import org.eclipse.jgit.lfs.lib.Constants;
+import org.eclipse.jgit.lib.ConfigConstants;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.util.LfsFactory;
+
+/**
+ * Implementation of {@link LfsFactory}, using built-in (optional) LFS support.
+ *
+ * @since 4.11
+ */
+public class BuiltinLFS extends LfsFactory {
+
+	private BuiltinLFS() {
+		SmudgeFilter.register();
+		CleanFilter.register();
+	}
+
+	/**
+	 * Activates the built-in LFS support.
+	 */
+	public static void register() {
+		setInstance(new BuiltinLFS());
+	}
+
+	@Override
+	public boolean isAvailable() {
+		return true;
+	}
+
+	@Override
+	public ObjectLoader applySmudgeFilter(Repository db, ObjectLoader loader,
+			Attribute attribute) throws IOException {
+		if (isEnabled(db) && (attribute == null || isEnabled(db, attribute))) {
+			return LfsBlobFilter.smudgeLfsBlob(db, loader);
+		} else {
+			return loader;
+		}
+	}
+
+	@Override
+	public LfsInputStream applyCleanFilter(Repository db, InputStream input,
+			long length, Attribute attribute) throws IOException {
+		if (isEnabled(db, attribute)) {
+			return new LfsInputStream(LfsBlobFilter.cleanLfsBlob(db, input));
+		} else {
+			return new LfsInputStream(input, length);
+		}
+	}
+
+	@Override
+	public @Nullable PrePushHook getPrePushHook(Repository repo,
+			PrintStream outputStream) {
+		if (isEnabled(repo)) {
+			return new LfsPrePushHook(repo, outputStream);
+		}
+		return null;
+	}
+
+	/**
+	 * @param db
+	 *            the repository
+	 * @return whether LFS is requested for the given repo.
+	 */
+	private boolean isEnabled(Repository db) {
+		if (db == null) {
+			return false;
+		}
+		return db.getConfig().getBoolean(ConfigConstants.CONFIG_FILTER_SECTION,
+				Constants.LFS, ConfigConstants.CONFIG_KEY_USEJGITBUILTIN,
+				false);
+	}
+
+	/**
+	 * @param db
+	 *            the repository
+	 * @param attribute
+	 *            the attribute to check
+	 * @return whether LFS filter is enabled for the given .gitattribute
+	 *         attribute.
+	 */
+	private boolean isEnabled(Repository db, Attribute attribute) {
+		if (attribute == null) {
+			return false;
+		}
+		return isEnabled(db) && Constants.LFS.equals(attribute.getValue());
+	}
+
+}
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/CleanFilter.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/CleanFilter.java
index 3e6f9961a8..fccbae7955 100644
--- a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/CleanFilter.java
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/CleanFilter.java
@@ -91,7 +91,7 @@ public class CleanFilter extends FilterCommand {
 	 * Registers this filter by calling
 	 * {@link FilterCommandRegistry#register(String, FilterCommandFactory)}
 	 */
-	public final static void register() {
+	static void register() {
 		FilterCommandRegistry
 				.register(org.eclipse.jgit.lib.Constants.BUILTIN_FILTER_PREFIX
 						+ Constants.ATTR_FILTER_DRIVER_PREFIX
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobFilter.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobFilter.java
new file mode 100644
index 0000000000..a7d218f803
--- /dev/null
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobFilter.java
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2017, Markus Duft <markus.duft@ssi-schaefer.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.lfs;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.util.TemporaryBuffer;
+import org.eclipse.jgit.util.TemporaryBuffer.LocalFile;
+
+/**
+ * Provides transparently either a stream to the blob or a LFS media file if
+ * managed by LFS.
+ *
+ * @since 4.11
+ */
+public class LfsBlobFilter {
+
+	/**
+	 * In case the given {@link ObjectLoader} points to a LFS pointer file
+	 * replace the loader with one pointing to the LFS media file contents.
+	 * Missing LFS files are downloaded on the fly - same logic as the smudge
+	 * filter.
+	 *
+	 * @param db
+	 *            the repo
+	 * @param loader
+	 *            the loader for the blob
+	 * @return either the original loader, or a loader for the LFS media file if
+	 *         managed by LFS. Files are downloaded on demand if required.
+	 * @throws IOException
+	 *             in case of an error
+	 */
+	public static ObjectLoader smudgeLfsBlob(Repository db, ObjectLoader loader)
+			throws IOException {
+		if (loader.getSize() > LfsPointer.SIZE_THRESHOLD) {
+			return loader;
+		}
+
+		try (InputStream is = loader.openStream()) {
+			LfsPointer ptr = LfsPointer.parseLfsPointer(is);
+			if (ptr != null) {
+				Lfs lfs = new Lfs(db);
+				AnyLongObjectId oid = ptr.getOid();
+				Path mediaFile = lfs.getMediaFile(oid);
+				if (!Files.exists(mediaFile)) {
+					SmudgeFilter.downloadLfsResource(lfs, db, ptr);
+				}
+
+				return new LfsBlobLoader(mediaFile);
+			}
+		}
+
+		return loader;
+	}
+
+	/**
+	 * Run the LFS clean filter on the given stream and return a stream to the
+	 * LFS pointer file buffer. Used when inserting objects.
+	 *
+	 * @param db
+	 *            the {@link Repository}
+	 * @param originalContent
+	 *            the {@link InputStream} to the original content
+	 * @return a {@link TemporaryBuffer} representing the LFS pointer. The
+	 *         caller is responsible to destroy the buffer.
+	 * @throws IOException
+	 *             in case of any error.
+	 */
+	public static TemporaryBuffer cleanLfsBlob(Repository db,
+			InputStream originalContent) throws IOException {
+		LocalFile buffer = new TemporaryBuffer.LocalFile(null);
+		CleanFilter f = new CleanFilter(db, originalContent, buffer);
+		try {
+			while (f.run() != -1) {
+				// loop as long as f.run() tells there is work to do
+			}
+		} catch (IOException e) {
+			buffer.destroy();
+			throw e;
+		}
+		return buffer;
+	}
+
+}
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobLoader.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobLoader.java
new file mode 100644
index 0000000000..697ae47a68
--- /dev/null
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsBlobLoader.java
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2017, Markus Duft <markus.duft@ssi-schaefer.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.lfs;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+
+import org.eclipse.jgit.errors.LargeObjectException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectStream;
+import org.eclipse.jgit.storage.pack.PackConfig;
+import org.eclipse.jgit.util.IO;
+
+/**
+ * An {@link ObjectLoader} implementation that reads a media file from the LFS
+ * storage.
+ *
+ * @since 4.11
+ */
+public class LfsBlobLoader extends ObjectLoader {
+
+	private Path mediaFile;
+
+	private BasicFileAttributes attributes;
+
+	private byte[] cached;
+
+	/**
+	 * Create a loader for the LFS media file at the given path.
+	 *
+	 * @param mediaFile
+	 *            path to the file
+	 * @throws IOException
+	 *             in case of an error reading attributes
+	 */
+	public LfsBlobLoader(Path mediaFile) throws IOException {
+		this.mediaFile = mediaFile;
+		this.attributes = Files.readAttributes(mediaFile,
+				BasicFileAttributes.class);
+	}
+
+	@Override
+	public int getType() {
+		return Constants.OBJ_BLOB;
+	}
+
+	@Override
+	public long getSize() {
+		return attributes.size();
+	}
+
+	@Override
+	public byte[] getCachedBytes() throws LargeObjectException {
+		if (getSize() > PackConfig.DEFAULT_BIG_FILE_THRESHOLD) {
+			throw new LargeObjectException();
+		}
+
+		if (cached == null) {
+			try {
+				cached = IO.readFully(mediaFile.toFile());
+			} catch (IOException ioe) {
+				throw new LargeObjectException(ioe);
+			}
+		}
+		return cached;
+	}
+
+	@Override
+	public ObjectStream openStream()
+			throws MissingObjectException, IOException {
+		return new ObjectStream.Filter(getType(), getSize(),
+				Files.newInputStream(mediaFile));
+	}
+
+}
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/SmudgeFilter.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/SmudgeFilter.java
index ae7fab83af..142e74df6a 100644
--- a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/SmudgeFilter.java
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/SmudgeFilter.java
@@ -100,9 +100,9 @@ public class SmudgeFilter extends FilterCommand {
 	};
 
 	/**
-	 * Registers this filter in JGit by calling
+	 * Register this filter in JGit
 	 */
-	public final static void register() {
+	static void register() {
 		FilterCommandRegistry
 				.register(org.eclipse.jgit.lib.Constants.BUILTIN_FILTER_PREFIX
 						+ Constants.ATTR_FILTER_DRIVER_PREFIX
@@ -110,8 +110,6 @@ public class SmudgeFilter extends FilterCommand {
 						FACTORY);
 	}
 
-	private Lfs lfs;
-
 	/**
 	 * Constructor for SmudgeFilter.
 	 *
@@ -126,13 +124,13 @@ public class SmudgeFilter extends FilterCommand {
 	public SmudgeFilter(Repository db, InputStream in, OutputStream out)
 			throws IOException {
 		super(in, out);
-		lfs = new Lfs(db);
+		Lfs lfs = new Lfs(db);
 		LfsPointer res = LfsPointer.parseLfsPointer(in);
 		if (res != null) {
 			AnyLongObjectId oid = res.getOid();
 			Path mediaFile = lfs.getMediaFile(oid);
 			if (!Files.exists(mediaFile)) {
-				downloadLfsResource(db, res);
+				downloadLfsResource(lfs, db, res);
 			}
 			this.in = Files.newInputStream(mediaFile);
 		}
@@ -141,6 +139,8 @@ public class SmudgeFilter extends FilterCommand {
 	/**
 	 * Download content which is hosted on a LFS server
 	 *
+	 * @param lfs
+	 *            local {@link Lfs} storage.
 	 * @param db
 	 *            the repository to work with
 	 * @param res
@@ -148,9 +148,8 @@ public class SmudgeFilter extends FilterCommand {
 	 * @return the paths of all mediafiles which have been downloaded
 	 * @throws IOException
 	 */
-	private Collection<Path> downloadLfsResource(Repository db,
-			LfsPointer... res)
-			throws IOException {
+	public static Collection<Path> downloadLfsResource(Lfs lfs, Repository db,
+			LfsPointer... res) throws IOException {
 		Collection<Path> downloadedPaths = new ArrayList<>();
 		Map<String, LfsPointer> oidStr2ptr = new HashMap<>();
 		for (LfsPointer p : res) {
diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/lib/Constants.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/lib/Constants.java
index fbfbf377bd..835d7be02b 100644
--- a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/lib/Constants.java
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/lib/Constants.java
@@ -56,7 +56,7 @@ import org.eclipse.jgit.lfs.internal.LfsText;
 @SuppressWarnings("nls")
 public final class Constants {
 	/**
-	 * lfs folder
+	 * lfs folder/section/filter name
 	 *
 	 * @since 4.6
 	 */