Throw API exception when MergeCommand hits checkout conflicts

When MergeCommand hit checkout conflicts it did throw an internal JGit
exception org.eclipse.jgit.errors.CheckoutConflictException instead of
org.eclipse.jgit.api.errors.CheckoutConflictException which it
declares to throw. Hence translate the internal exception to the
exception declared in the API.

Bug: 327573
Change-Id: I1efcd93a43ecbf4a40583e0fc9d8d53cffc98cae
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java

@@ -46,6 +46,7 @@ package org.eclipse.jgit.api;
 import java.io.IOException;
 import java.text.MessageFormat;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -122,6 +123,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 									Integer.valueOf(commits.size())));
 
 		RevWalk revWalk = null;
+		DirCacheCheckout dco = null;
 		try {
 			Ref head = repo.getRef(Constants.HEAD);
 			if (head == null)
@@ -147,7 +149,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 			ObjectId headId = head.getObjectId();
 			if (headId == null) {
 				revWalk.parseHeaders(srcCommit);
-				DirCacheCheckout dco = new DirCacheCheckout(repo,
+				dco = new DirCacheCheckout(repo,
 						repo.lockDirCache(), srcCommit.getTree());
 				dco.setFailOnConflict(true);
 				dco.checkout();
@@ -176,7 +178,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 				// FAST_FORWARD detected: skip doing a real merge but only
 				// update HEAD
 				refLogMessage.append(": " + MergeStatus.FAST_FORWARD);
-				DirCacheCheckout dco = new DirCacheCheckout(repo,
+				dco = new DirCacheCheckout(repo,
 						headCommit.getTree(), repo.lockDirCache(),
 						srcCommit.getTree());
 				dco.setFailOnConflict(true);
@@ -214,7 +216,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 				refLogMessage.append(mergeStrategy.getName());
 				refLogMessage.append('.');
 				if (noProblems) {
-					DirCacheCheckout dco = new DirCacheCheckout(repo,
+					dco = new DirCacheCheckout(repo,
 							headCommit.getTree(), repo.lockDirCache(),
 							merger.getResultTreeId());
 					dco.setFailOnConflict(true);
@@ -250,6 +252,10 @@ public class MergeCommand extends GitCommand<MergeResult> {
 					}
 				}
 			}
+		} catch (org.eclipse.jgit.errors.CheckoutConflictException e) {
+			List<String> conflicts = (dco == null) ? Collections
+					.<String> emptyList() : dco.getConflicts();
+			throw new CheckoutConflictException(conflicts, e);
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					MessageFormat.format(

org.eclipse.jgit/src/org/eclipse/jgit/api/errors/CheckoutConflictException.java

@@ -48,6 +48,20 @@ public class CheckoutConflictException extends GitAPIException {
 	private static final long serialVersionUID = 1L;
 	private List<String> conflictingPaths;
 
+	/**
+	 * Translate internal exception to API exception
+	 *
+	 * @param conflictingPaths
+	 *            list of conflicting paths
+	 *
+	 * @param e
+	 */
+	public CheckoutConflictException(List<String> conflictingPaths,
+			org.eclipse.jgit.errors.CheckoutConflictException e) {
+		super(e.getMessage(), e);
+		this.conflictingPaths = conflictingPaths;
+	}
+
 	CheckoutConflictException(String message, Throwable cause) {
 		super(message, cause);
 	}
@@ -73,6 +87,7 @@ public class CheckoutConflictException extends GitAPIException {
 
 	/**
 	 * Adds a new conflicting path
+	 *
 	 * @param conflictingPath
 	 * @return {@code this}
 	 */