Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/6120#discussion_r203021961
--- Diff:
flink-core/src/test/java/org/apache/flink/api/java/typeutils/LambdaExtractionTest.java
---
@@ -50,12 +41,12 @@
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.assertTrue;
/**
- * Tests the type extractor for lambda functions.
+ * Tests the type extractor for lambda functions. Many tests only work if
the compiler supports
--- End diff --
A flat map can not work by definition because it contains generics. I will
add some tests for the `returns`.
---
