public RetResult<T> attach(String key, Object value) {
        if (this.attach == null) this.attach = new HashMap<>();
        boolean canstr = value != null && (value instanceof CharSequence || value instanceof Number || value.getClass().isPrimitive());
        this.attach.put(key, value == null ? null : (canstr ? String.valueOf(value) : JsonConvert.root().convertTo(value)));
        return this;
    }
public RetResult < T > attach ( String key , Object value ) { if ( this . attach == null ) this . attach = new HashMap < > ( ) ; boolean canstr = value != null && ( value instanceof CharSequence || value instanceof Number || value . getClass ( ) . isPrimitive ( ) ) ; this . attach . put ( key , value == null ? null : ( canstr ? String . valueOf ( value ) : JsonConvert . root ( ) . convertTo ( value ) ) ) ; return this ; }
attach添加元素

@param key   String
@param value String

@return RetResult