Add missing @since tags

Change-Id: I6f672249d7ca014c63fb939cd0836689eb27ab90
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransferConfig.java

@@ -87,6 +87,7 @@ public class TransferConfig {
 
 	/**
 	 * @return allow clients to request non-advertised tip SHA-1s?
+	 * @since 3.1
 	 */
 	public boolean isAllowTipSha1InWant() {
 		return allowTipSha1InWant;
@@ -94,6 +95,7 @@ public class TransferConfig {
 
 	/**
 	 * @return {@link RefFilter} respecting configured hidden refs.
+	 * @since 3.1
 	 */
 	public RefFilter getRefFilter() {
 		if (hideRefs.length == 0)