Cleaned up some javadocs.

briar-api/src/org/briarproject/api/sync/Ack.java

@@ -2,7 +2,7 @@ package org.briarproject.api.sync;
 
 import java.util.Collection;
 
-/** A packet acknowledging receipt of one or more {@link Message}s. */
+/** A packet acknowledging receipt of one or more {@link Message Messages}. */
 public class Ack {
 
 	private final Collection<MessageId> acked;

briar-api/src/org/briarproject/api/sync/Offer.java

@@ -2,7 +2,7 @@ package org.briarproject.api.sync;
 
 import java.util.Collection;
 
-/** A packet offering the recipient one or more {@link Message}s. */
+/** A packet offering the recipient one or more {@link Message Messages}. */
 public class Offer {
 
 	private final Collection<MessageId> offered;

briar-api/src/org/briarproject/api/sync/Request.java

@@ -2,7 +2,9 @@ package org.briarproject.api.sync;
 
 import java.util.Collection;
 
-/** A packet requesting one or more {@link Message}s from the recipient. */
+/**
+ * A packet requesting one or more {@link Message Messages} from the recipient.
+ */
 public class Request {
 
 	private final Collection<org.briarproject.api.sync.MessageId> requested;