question: boolean updateValueType ( Object value ) { if ( _valueTypeFinallySet || value == null ) return _valueTypeFinallySet ; Class < ? > type = value . getClass ( ) ; if ( _valueType == null ) { synchronized ( this ) { if ( _valueType == null ) _valueType = type ; } } else if ( _valueType != type && ! _valueType . isAssignableFrom ( type ) ) { synchronized ( this ) { _valueType = TypeDataIndex . getCommonSuperType ( type , _valueType ) ; } } if ( _valueType == Object . class ) _valueTypeFinallySet = true ; return _valueTypeFinallySet ; }
target:  set the value type if needed, returns true if the type is finally set