Adjust javadoc to pass errorprone checks

bazel build //org.eclipse.jgit.test:all doesn't build due to
errorprone errors. This leds to disabling the checks and find the
errors later in the jenkins builder.

Fix javadoc errors reported by errorprone. This doesn't fix completely
the build but it is a step towards it.

Change-Id: Ic4ec93a2d71d4628bf3a05277c60157881156393

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcTestCase.java

@@ -61,6 +61,7 @@ public void tearDown() throws Exception {
 	 *            the depth of the commit chain.
 	 * @return the commit that is the tip of the commit chain
 	 * @throws Exception
+	 *             if an error occurred
 	 */
 	protected RevCommit commitChain(int depth) throws Exception {
 		if (depth <= 0)
@@ -93,6 +94,7 @@ protected RevCommit commitChain(int depth) throws Exception {
 	 *            number of files added per commit
 	 * @return the commit that is the tip of the commit chain
 	 * @throws Exception
+	 *             if an error occurred
 	 */
 	protected RevCommit commitChain(int depth, int width) throws Exception {
 		if (depth <= 0) {

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackIndexTestCase.java

@@ -66,7 +66,9 @@ public void setUp() throws Exception {
 	 * Verify CRC32 support.
 	 *
 	 * @throws MissingObjectException
+	 *             object is missing in the underlying index
 	 * @throws UnsupportedOperationException
+	 *             the index doesn't have CRC
 	 */
 	public abstract void testCRC32() throws MissingObjectException,
 			UnsupportedOperationException;

org.eclipse.jgit.test/tst/org/eclipse/jgit/test/resources/SampleDataRepositoryTestCase.java

@@ -35,6 +35,7 @@ public void setUp() throws Exception {
 	 * @param repo
 	 *            test repository to receive packfile copies
 	 * @throws IOException
+	 *             an error occurred
 	 */
 	public static void copyCGitTestPacks(FileRepository repo) throws IOException {
 		final String[] packs = {

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/RequestValidatorTestCase.java

@@ -70,20 +70,30 @@ public void setUp() throws Exception {
 	}
 
 	/**
+	 * Check if the validator accepts a reachable commit
+	 *
 	 * @return true if a commit reachable from a visible tip (but not directly
 	 *         the tip) is valid
 	 */
 	protected abstract boolean isReachableCommitValid();
 
-	/** @return true if a commit not reachable from any tip is valid */
+	/**
+	 * Check if the validator accepts an unreachable commit
+	 *
+	 * @return true if a commit not reachable from any tip is valid
+	 **/
 	protected abstract boolean isUnreachableCommitValid();
 
 	/**
+	 * Check if the validator accepts a previously advertised tip
+	 *
 	 * @return true if the commit directly pointed by an advertised ref is valid
 	 */
 	protected abstract boolean isAdvertisedTipValid();
 
 	/**
+	 * Check if the validator accepts a previous unadvertised tip
+	 *
 	 * @return true if the object directly pointed by a non-advertised ref is
 	 *         valid
 	 */
@@ -92,17 +102,23 @@ public void setUp() throws Exception {
 	// UploadPack doesn't allow to ask for blobs when there is no
 	// bitmap. Test both cases separately.
 	/**
+	 * Check if the validator accepts a reachable blob (repo with bitmaps)
+	 *
 	 * @return true if a reachable blob is valid (and the repo has bitmaps)
 	 */
 	protected abstract boolean isReachableBlobValid_withBitmaps();
 
 	/**
+	 * Check if the validator accepts a reachable blob (repo without bitmaps)
+	 *
 	 * @return true if a reachable blob is valid (and the repo does NOT have
 	 *         bitmaps)
 	 */
 	protected abstract boolean isReachableBlobValid_withoutBitmaps();
 
 	/**
+	 * Check if the validator accepts an unreachable blob
+	 *
 	 * @return true if a blob unreachable from any tip is valid
 	 */
 	protected abstract boolean isUnreachableBlobValid();