Issue #1724: Add a test for the interop case where we set sealed on classes with only private/default access constructors.
Issue #1724: Implement the interop functionality for java classes with only private and default access constructors
Issue #1724: Now java classes can be sealed these tests pick up an additional error.
Issue #1725: Add a test
Fix #1725.
Fix #1726: The return type shouldn't matter when determining whether a method overloads a superclass method -- it's just the name and the parameter types. String.() was incorrectly being marked as overloaded which mean that it wasn't found as a member which meant we found List.clone().
Issue #1726: Add a test