Fix broken codegen with fields with same type

[gaberudy]

Pop the crossReferenceKeyList after recursing down so that codegen succeeds when two siblings have the same complex type.

[timqian]

This change makes the code only check one level of parent-child relation, and will pop every crossReferenceKey (parent-child relation) away, I think it will result in bug for recursive schema. And besides, manipulating pointer parameter in recursive function make the code hard to reason about