Cross-language invocation Part 1: Java calling Python functions and actors (#4166)

java/test/src/main/resources/test_cross_language_invocation.py

@@ -0,0 +1,20 @@
+# This file is used by CrossLanguageInvocationTest.java to test cross-language
+# invocation.
+import ray
+import six
+
+
+@ray.remote
+def py_func(value):
+    assert isinstance(value, bytes)
+    return b"Response from Python: " + value
+
+
+@ray.remote
+class Counter(object):
+    def __init__(self, value):
+        self.value = int(value)
+
+    def increase(self, delta):
+        self.value += int(delta)
+        return str(self.value).encode("utf-8") if six.PY3 else str(self.value)