DATACMNS-578 - Speed up instance creation by generating Factory classes with ASM.

Cleaned up byte code generation and removed usage of JDK 8 specific types.
DATACMNS-578 - Speed up instance creation by generating Factory classes with ASM.

Added support for unboxing of constructor parameters and more robust handling for cases where we cannot generate a custom ObjectInstantiator. In such cases we'll fall back to the ReflectiveEntityInstantiator.