在PHP 7中实现的规范。不可变
该库的目的是确保所生成的JSON API文档的严格有效性。
JSON：
{
" data " : {
" type " : " articles " ,
" id " : " 1 " ,
" attributes " : {
" title " : " Rails is Omakase "
},
" relationships " : {
" author " : {
" data " : {
" type " : " people " ,
" id " : " 9 "
},
" links " : {
" self " : " /articles/1/relationships/author " ,
