Merge "Add null checks"

tools/lint/checks/src/main/java/com/google/android/lint/EnforcePermissionDetector.kt

@@ -65,8 +65,16 @@ class EnforcePermissionDetector : Detector(), SourceCodeScanner {
             if (attr1[i].name != attr2[i].name) {
                 return false
             }
-            val v1 = ConstantEvaluator.evaluate(context, attr1[i].value)
+            val value1 = attr1[i].value
-            val v2 = ConstantEvaluator.evaluate(context, attr2[i].value)
+            val value2 = attr2[i].value
+            if (value1 == null && value2 == null) {
+                continue
+            }
+            if (value1 == null || value2 == null) {
+                return false
+            }
+            val v1 = ConstantEvaluator.evaluate(context, value1)
+            val v2 = ConstantEvaluator.evaluate(context, value2)
             if (v1 != v2) {
                 return false
             }