add javac problemMatcher

.github/java.json

@@ -9,6 +9,18 @@
                     "message": 3
                 }
             ]
-        }
+        },
+    	{
+			"owner": "javac",
+			"pattern": [
+				{
+					"regexp": "^([^:]+):(\\d+): (warning|error): (.+?)$",
+					"file": 1,
+					"line": 2,
+					"severity": 3,
+					"message": 4
+				}
+			]
+       }
     ]
 }