output: #fixed code
                                 @Override
     public Field<O> setLiteralInitializer(final String value)
     {
        String stub = "public class Stub { private String stub = " + value + " }";
        JavaClass temp = (JavaClass) JavaParser.parse(stub);
        VariableDeclarationFragment tempFrag = (VariableDeclarationFragment) temp.getFields().get(0).getInternal();
        fragment.setInitializer((Expression) ASTNode.copySubtree(ast, tempFrag.getInitializer()));
        return this;
     }
input: #vulnerable code 
                                 @Override
     public Field<O> setLiteralInitializer(final String value)
     {
        String stub = "public class Stub { private String stub = " + value + " }";
        JavaClass temp = (JavaClass) JavaParser.parse(stub);
        FieldDeclaration internal = (FieldDeclaration) temp.getFields().get(0).getInternal();
  
        for (Object f : internal.fragments())
        {
           if (f instanceof VariableDeclarationFragment)
           {
              VariableDeclarationFragment tempFrag = (VariableDeclarationFragment) f;
              VariableDeclarationFragment localFrag = getFragment(field);
              localFrag.setInitializer((Expression) ASTNode.copySubtree(ast, tempFrag.getInitializer()));
              break;
           }
        }
  
        return this;
     } 
                              #location 14 
                              #vulnerability type NULL_DEREFERENCE