A.5 Interfaces

  InterfaceDeclaration:   interface BindingIdentifier TypeParameters_opt InterfaceExtendsClause_opt ObjectType

  InterfaceExtendsClause:   extends ClassOrInterfaceTypeList

  ClassOrInterfaceTypeList:   ClassOrInterfaceType   ClassOrInterfaceTypeList , ClassOrInterfaceType

  ClassOrInterfaceType:   TypeReference