Add Nullable and NotNull annotations to getTarget and getTemplates methods
Handle missing code generation Target in LeftRecursiveRuleAnalyzer
Handle missing code generation Target in LexerATNFactory
Handle missing code generation Target in CodeGenerator methods: unexpected code paths now throw UnsupportedOperationException
Handle missing code generation Target in CodeGenPipeline
Handle missing code generation Target in BuildDependencyGenerator
Add additional regression test for #649
Add OutputModelFactory.getTarget(), which does not require the null checks of CodeGenerator.getTarget()
Use OutputModelFactory.getTarget instead of CodeGenerator.getTarget where appropriate