A flag in the JDR to govern usage of platform types
Flexible types added to JDR

So far they act exactly like inflexible ones
Fix compilation errors
Render flexible types in debug mode
Tests for Java method calls
Support flexible types in TypeCheckingProcedure
Minor. DelegatingFlexibleType moved to top level
TypeSubstitutor respects flexible types
Support flexible types in DataFlowValues
Fix the case of safe call and elvis operators: flexible types may be nullable
Test data fixed
Supertypes should not be flexible
Failing test isolated
Equality for flexible types
Support forced resolve for lazy flexible types
Better support for forced resolve while debugging
Rendering flexible types with "!" and optional parts
Don't create platform types for annotation members
Make not-null compile-time constants non-flexible
Don't create flexible types for ".class" expressions in annotation arguments