Mark fetch requests fields as final and @NonNull when possible

Mark reference fields as final, annotate constructor parameters and
getters as @NonNull when appropiate and assert the incoming references
are non-null.

Change-Id: I0ef9a513a99313bf461fe9629ce6cc8b409bdedb
Signed-off-by: Ivan Frade <ifrade@google.com>

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

@@ -42,6 +42,8 @@
  */
 package org.eclipse.jgit.transport;
 
+import static java.util.Objects.requireNonNull;
+
 import java.util.Set;
 
 import org.eclipse.jgit.annotations.NonNull;
@@ -76,19 +78,14 @@ abstract class FetchRequest {
 	 * @param clientCapabilities
 	 *            capabilities sent in the request
 	 */
-	FetchRequest(Set<ObjectId> wantIds, int depth,
+	FetchRequest(@NonNull Set<ObjectId> wantIds, int depth,
-			Set<ObjectId> clientShallowCommits, long filterBlobLimit,
+			@NonNull Set<ObjectId> clientShallowCommits, long filterBlobLimit,
-			Set<String> clientCapabilities) {
+			@NonNull Set<String> clientCapabilities) {
-		if (wantIds == null || clientShallowCommits == null
+		this.wantIds = requireNonNull(wantIds);
-				|| clientCapabilities == null) {
-			throw new NullPointerException();
-		}
-
-		this.wantIds = wantIds;
 		this.depth = depth;
-		this.clientShallowCommits = clientShallowCommits;
+		this.clientShallowCommits = requireNonNull(clientShallowCommits);
 		this.filterBlobLimit = filterBlobLimit;
-		this.clientCapabilities = clientCapabilities;
+		this.clientCapabilities = requireNonNull(clientCapabilities);
 	}
 
 	/**

org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchV0Request.java

@@ -46,6 +46,7 @@ import java.util.Collection;
 import java.util.HashSet;
 import java.util.Set;
 
+import org.eclipse.jgit.annotations.NonNull;
 import org.eclipse.jgit.lib.ObjectId;
 
 /**
@@ -53,9 +54,9 @@ import org.eclipse.jgit.lib.ObjectId;
  */
 final class FetchV0Request extends FetchRequest {
 
-	FetchV0Request(Set<ObjectId> wantIds, int depth,
+	FetchV0Request(@NonNull Set<ObjectId> wantIds, int depth,
-			Set<ObjectId> clientShallowCommits, long filterBlobLimit,
+			@NonNull Set<ObjectId> clientShallowCommits, long filterBlobLimit,
-			Set<String> clientCapabilities) {
+			@NonNull Set<String> clientCapabilities) {
 		super(wantIds, depth, clientShallowCommits, filterBlobLimit,
 				clientCapabilities);
 	}
@@ -64,13 +65,13 @@ final class FetchV0Request extends FetchRequest {
 
 		int depth;
 
-		Set<ObjectId> wantIds = new HashSet<>();
+		final Set<ObjectId> wantIds = new HashSet<>();
 
-		Set<ObjectId> clientShallowCommits = new HashSet<>();
+		final Set<ObjectId> clientShallowCommits = new HashSet<>();
 
 		long filterBlobLimit = -1;
 
-		Set<String> clientCaps = new HashSet<>();
+		final Set<String> clientCaps = new HashSet<>();
 
 		/**
 		 * @param objectId

org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchV2Request.java

@@ -42,6 +42,8 @@
  */
 package org.eclipse.jgit.transport;
 
+import static java.util.Objects.requireNonNull;
+
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -71,16 +73,18 @@ public final class FetchV2Request extends FetchRequest {
 
 	private final boolean doneReceived;
 
-	private FetchV2Request(List<ObjectId> peerHas,
+	FetchV2Request(@NonNull List<ObjectId> peerHas,
-			TreeMap<String, ObjectId> wantedRefs, Set<ObjectId> wantIds,
+			@NonNull TreeMap<String, ObjectId> wantedRefs,
-			Set<ObjectId> clientShallowCommits, int deepenSince,
+			@NonNull Set<ObjectId> wantIds,
-			List<String> deepenNotRefs, int depth, long filterBlobLimit,
+			@NonNull Set<ObjectId> clientShallowCommits, int deepenSince,
-			boolean doneReceived, Set<String> clientCapabilities) {
+			@NonNull List<String> deepenNotRefs, int depth,
+			long filterBlobLimit,
+			boolean doneReceived, @NonNull Set<String> clientCapabilities) {
 		super(wantIds, depth, clientShallowCommits, filterBlobLimit, clientCapabilities);
-		this.peerHas = peerHas;
+		this.peerHas = requireNonNull(peerHas);
-		this.wantedRefs = wantedRefs;
+		this.wantedRefs = requireNonNull(wantedRefs);
 		this.deepenSince = deepenSince;
-		this.deepenNotRefs = deepenNotRefs;
+		this.deepenNotRefs = requireNonNull(deepenNotRefs);
 		this.doneReceived = doneReceived;
 	}
 
@@ -134,17 +138,17 @@ public final class FetchV2Request extends FetchRequest {
 
 	/** A builder for {@link FetchV2Request}. */
 	static final class Builder {
-		List<ObjectId> peerHas = new ArrayList<>();
+		final List<ObjectId> peerHas = new ArrayList<>();
 
-		TreeMap<String, ObjectId> wantedRefs = new TreeMap<>();
+		final TreeMap<String, ObjectId> wantedRefs = new TreeMap<>();
 
-		Set<ObjectId> wantIds = new HashSet<>();
+		final Set<ObjectId> wantIds = new HashSet<>();
 
-		Set<ObjectId> clientShallowCommits = new HashSet<>();
+		final Set<ObjectId> clientShallowCommits = new HashSet<>();
 
-		List<String> deepenNotRefs = new ArrayList<>();
+		final List<String> deepenNotRefs = new ArrayList<>();
 
-		Set<String> clientCapabilities = new HashSet<>();
+		final Set<String> clientCapabilities = new HashSet<>();
 
 		int depth;