Make inner classes static where possible

As reported by Error Prone:

An inner class should be static unless it references members of its
enclosing class. An inner class that is made non-static unnecessarily
uses more memory and does not make the intent of the class clear.

See https://errorprone.info/bugpattern/ClassCanBeStatic

Change-Id: Ib99d120532630dba63cf400cc1c61c318286fc41
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
(cherry picked from commit ee40efcea4)

org.eclipse.jgit.http.test/tst/org/eclipse/jgit/transport/http/apache/HttpClientConnectionTest.java

@@ -76,7 +76,7 @@ public void testGetHeaderFieldsAllowMultipleValues()
 		assertTrue(headerValues.contains("NTLM"));
 	}
 
-	private class HttpResponseMock extends AbstractHttpMessage
+	private static class HttpResponseMock extends AbstractHttpMessage
 			implements HttpResponse {
 		@Override
 		public StatusLine getStatusLine() {

org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java

@@ -70,7 +70,7 @@
  * Mock {@link org.eclipse.jgit.util.SystemReader} for tests.
  */
 public class MockSystemReader extends SystemReader {
-	private final class MockConfig extends FileBasedConfig {
+	private static final class MockConfig extends FileBasedConfig {
 		private MockConfig(File cfgLocation, FS fs) {
 			super(cfgLocation, fs);
 		}

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/TextHashFunctions.java

@@ -474,7 +474,7 @@ private static abstract class Fold {
 	}
 
 	/** Utility to help us identify unique lines in a file. */
-	private class Line {
+	private static class Line {
 		private final RawText txt;
 
 		private final int pos;

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/ArchiveCommandTest.java

@@ -190,7 +190,8 @@ public void archiveByDirectoryPath() throws GitAPIException, IOException {
 		}
 	}
 
-	private class MockFormat implements ArchiveCommand.Format<MockOutputStream> {
+	private static class MockFormat
+			implements ArchiveCommand.Format<MockOutputStream> {
 
 		private Map<String, String> entries = new HashMap<>();
 
@@ -240,7 +241,7 @@ public Iterable<String> suffixes() {
 		}
 	}
 
-	public class MockOutputStream extends OutputStream {
+	public static class MockOutputStream extends OutputStream {
 
 		private int foo;
 

org.eclipse.jgit.test/tst/org/eclipse/jgit/gitrepo/RepoCommandTest.java

@@ -139,7 +139,7 @@ public void setUp() throws Exception {
 		resolveRelativeUris();
 	}
 
-	class IndexedRepos implements RepoCommand.RemoteReader {
+	static class IndexedRepos implements RepoCommand.RemoteReader {
 		Map<String, Repository> uriRepoMap;
 		IndexedRepos() {
 			uriRepoMap = new HashMap<>();

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

@@ -141,7 +141,7 @@ private void doCacheTests() throws IOException {
 		}
 	}
 
-	private class TestObject {
+	private static class TestObject {
 		ObjectId id;
 
 		int type;

org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/MergerTest.java

@@ -839,7 +839,7 @@ public ObjectReader newReader() {
 	/**
 	 * Throws an exception if reading beyond limit.
 	 */
-	class BigReadForbiddenStream extends ObjectStream.Filter {
+	static class BigReadForbiddenStream extends ObjectStream.Filter {
 		int limit;
 
 		BigReadForbiddenStream(ObjectStream orig, int limit) {
@@ -878,7 +878,7 @@ public int read(byte[] b, int off, int len) throws IOException {
 		}
 	}
 
-	class BigReadForbiddenReader extends ObjectReader.Filter {
+	static class BigReadForbiddenReader extends ObjectReader.Filter {
 		ObjectReader delegate;
 		int limit;
 

org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/PlotCommitListTest.java

@@ -56,7 +56,7 @@
 
 public class PlotCommitListTest extends RevWalkTestCase {
 
-	class CommitListAssert {
+	static class CommitListAssert {
 		private PlotCommitList<PlotLane> pcl;
 		private PlotCommit<PlotLane> current;
 		private int nextIndex = 0;

org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/AbstractTreeIteratorTest.java

@@ -66,7 +66,7 @@ private static String prefix(String path) {
 		return s > 0 ? path.substring(0, s) : "";
 	}
 
-	public class FakeTreeIterator extends WorkingTreeIterator {
+	public static class FakeTreeIterator extends WorkingTreeIterator {
 		public FakeTreeIterator(String pathName, FileMode fileMode) {
 			super(prefix(pathName), new Config().get(WorkingTreeOptions.KEY));
 			mode = fileMode.getBits();

org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/TimeoutOutputStreamTest.java

@@ -282,7 +282,7 @@ private static long now() {
 		return System.currentTimeMillis();
 	}
 
-	private final class FullPipeInputStream extends PipedInputStream {
+	private static final class FullPipeInputStream extends PipedInputStream {
 		FullPipeInputStream(PipedOutputStream src) throws IOException {
 			super(src);
 			src.write(new byte[PIPE_SIZE]);

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexRemapper.java

@@ -207,7 +207,7 @@ public EWAHCompressedBitmap getBitmap(AnyObjectId objectId) {
 	}
 
 	/** An entry in the old PackBitmapIndex. */
-	public final class Entry extends ObjectId {
+	public static final class Entry extends ObjectId {
 		private final int flags;
 
 		Entry(AnyObjectId src, int flags) {

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

@@ -823,7 +823,7 @@ private static RevObject safeParseOld(RevWalk rw, AnyObjectId oldId)
 	 * Handle the abstraction of storing a ref update. This is because both
 	 * updating and deleting of a ref have merge testing in common.
 	 */
-	private abstract class Store {
+	private static abstract class Store {
 		abstract Result execute(Result status) throws IOException;
 	}
 }