Avoid using @Nullable to annotate arrays

As described in the javadoc for org.eclipse.jgit.annotations.Nullable:

  Warning: Please do not use this annotation on arrays. Different
  annotation processors treat `@Nullable Object[]` differently: some
  treat it as an array of nullable objects, for consistency with
  versions of `Nullable` defined with `@Target TYPE_USE`, while others
  treat it as a nullable array of objects. JGit therefore avoids using
  this annotation on arrays altogether.

  See the checker-framework manual[1] for details.

  [1] http://types.cs.washington.edu/checker-framework/current/checker-framework-manual.html#faq-array-syntax-meaning

Change-Id: I14ffcf80adbb8145d797998de2f2fa6ab84c3ae3
Signed-off-by: Jonathan Nieder <jrn@google.com>

org.eclipse.jgit/src/org/eclipse/jgit/lib/Config.java

@@ -62,7 +62,6 @@ import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.events.ConfigChangedEvent;
 import org.eclipse.jgit.events.ConfigChangedListener;
@@ -1158,7 +1157,6 @@ public class Config {
 	 *             if something went wrong while reading the config
 	 * @since 4.10
 	 */
-	@Nullable
 	protected byte[] readIncludedConfig(String relPath)
 			throws ConfigInvalidException {
 		return null;

org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java

@@ -1981,7 +1981,6 @@ public abstract class Repository implements AutoCloseable {
 	 *         empty
 	 * @throws IOException
 	 */
-	@Nullable
 	private byte[] readGitDirectoryFile(String filename) throws IOException {
 		File file = new File(getDirectory(), filename);
 		try {

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevCommit.java

@@ -407,7 +407,7 @@ public class RevCommit extends RevObject {
 	 * @return contents of the gpg signature; null if the commit was not signed.
 	 * @since 5.1
 	 */
-	public final @Nullable byte[] getRawGpgSignature() {
+	public final byte[] getRawGpgSignature() {
 		final byte[] raw = buffer;
 		final byte[] header = {'g', 'p', 'g', 's', 'i', 'g'};
 		final int start = RawParseUtils.headerStart(header, raw, 0);

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java

@@ -57,7 +57,6 @@ import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.text.MessageFormat;
 
-import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.errors.LockFailedException;
 import org.eclipse.jgit.internal.JGitText;
@@ -281,7 +280,6 @@ public class FileBasedConfig extends StoredConfig {
 	 * @since 4.10
 	 */
 	@Override
-	@Nullable
 	protected byte[] readIncludedConfig(String relPath)
 			throws ConfigInvalidException {
 		final File file;