Added a 'source' for commands that may be passed around in the context

src/test/java/net/minecraft/commands/tree/RootCommandNodeTest.java

@@ -24,7 +24,7 @@ public class RootCommandNodeTest extends AbstractCommandNodeTest {
 
     @Test
     public void testParse() throws Exception {
-        assertThat(node.parse("foo bar baz", new CommandContextBuilder()), is("foo bar baz"));
+        assertThat(node.parse("foo bar baz", new CommandContextBuilder<Object>(new Object())), is("foo bar baz"));
     }
 
     @Test(expected = UnsupportedOperationException.class)