anchor.diff:      ;
   
   packageHeader
  -    : 'package' identifier semi?
  +    : ('package' identifier semi?)?
       ;
   
   importList
  
positive.code:     | userType
      ;
  
  simpleIdentifier
      : Identifier //soft keywords:
      | 'abstract'
      | 'annotation'
      | 'by'
  
negative.code:     : (modifiers? 'constructor' NL*)? classParameters
      ;
  
  classBody
      : '{' NL* classMemberDeclarations NL* '}'
      ;
  
  classParameters
      : '(' NL* (classParameter (NL* ',' NL* classParameter)*)? NL* ')'
      ;
  