Annotate Sets#of with @SafeVarArgs to prevent heap pollution warning

This prevents the warning:

  Potential heap pollution via varargs parameter

The method doesn't do any casting of types that would cause the heap
pollution, so it should be safe to add @SafeVarArgs.

See [1] for information about this warning.

[1] http://stackoverflow.com/a/12462259/381622

Change-Id: Ic6d252915ea44b4f1c385afecb98906cd2c54382
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.test/src/org/eclipse/jgit/lib/Sets.java

@@ -47,6 +47,7 @@ import java.util.HashSet;
 import java.util.Set;
 
 public class Sets {
+	@SafeVarargs
 	public static <T> Set<T> of(T... elements) {
 		Set<T> ret = new HashSet<T>();
 		for (T element : elements)