private String buildMethodKey(String methodName, String key) {
        return RpcConstants.HIDE_KEY_PREFIX + methodName + RpcConstants.HIDE_KEY_PREFIX + key;
    }
Buildmkey string.

@param methodName the method name
@param key        the key
@return the string
core/api/src/main/java/com/alipay/sofa/rpc/filter/FilterInvoker.java