++ some small fixes and renaming
++ moved mappingsClassesForWhenByEnum to GenerationState
When by String constants:
Generate TABLESWITCH/LOOKUPSWITCH bytecode operation for when operator by String constants
++ added some tests
When2Switch: check if entry set is not empty
When2Switch: generate ifnonnull check for nullable values before *switch-opcode
When2Switch: tests for non-literal expression in when by integral