[CORDA-481]: GH 965: Java 8 lambdas don't work properly in checkpointing (#1619)

docs/source/changelog.rst

@@ -10,6 +10,8 @@ UNRELEASED
 Release 1.0
 -----------
 
+* Java 8 lambdas now work property with Kryo during check-pointing.
+
 * String constants have been marked as ``const`` type in Kotlin, eliminating cases where functions of the form
   ``get<constant name>()`` were created for the Java API. These can now be referenced by their name directly.
 

docs/source/serialization.rst

@@ -38,6 +38,10 @@ It's reproduced here as an example of both ways you can do this for a couple of
 .. note:: Several of the core interfaces at the heart of Corda are already annotated and so any classes that implement
    them will automatically be whitelisted.  This includes `Contract`, `ContractState` and `CommandData`.
 
+.. warning:: Java 8 Lambda expressions are not serializable except in flow checkpoints, and then not by default. The syntax to declare a serializable Lambda
+expression that will work with Corda is ``Runnable r = (Runnable & Serializable) () -> System.out.println("Hello World");``, or
+``Callable<String> c = (Callable<String> & Serializable) () -> "Hello World";``.
+
 .. warning:: We will be replacing the use of Kryo in the serialization framework and so additional changes here are
    likely.