问生成的xtext方法在生成器中出错。

EN

'Feature' name=ID '{'
    'verb' verb= [Activity]
    'objects' '('(classes+=[Class] (','classes+=[Class])*)?')'
    'common' '('(common+=[Feature] (','common+=[Feature])*)?')'     
    'optional' '('(optional+=[Feature] (','optional+=[Feature])*)?')'
    'variabilities' '(' (variabilities+=[FeatureVariability] (','variabilities+=FeatureVariability])*)?')'  
    'generalization' '('(generalization+=[Feature] (','generalization+=Feature])*)?')'      
 '}';

         verb act1
         objects (C4, C3)
         common()
         optional(f32, f31)
         variabilities()    
         generalization()
        }

         verb act1
         objects (C1, C2, C3)
         common()
         optional(f31, f32)
         variabilities()    
         generalization()
    } 

Feature f31{


         verb act2
         objects (C3)
         common()
         optional()
         variabilities()    
         generalization()
    }


Feature f32{
         verb act1
         objects (C1, C2, C3)
         common()
         optional()
         variabilities()    
         generalization()
    }

         verb act1
         objects (C1, C2, C3)
         common()
         optional(f32, f31)
         variabilities()    
         generalization()
    }

         verb act1
         objects (C1, C4)
         common(f2)
         optional(f31)
         variabilities()          
         generalization()}