Resteasy 3.5.0.Final on App Engine standard env - NoSuchFieldError SERVER_SENT_EVENTS_TYPE
Resteasy 3.1.4.Final is an implementation of the JAX-RS-API 2.0.1 spec whereas 3.5.1.Final is an impl of the JAX-RS-API 2.1 spec
即 Resteasy 3.1.4.Final 对应 JAX-RS-API 2.0.1 spec，Resteasy 3.5.1.Final 对应JAX-RS-API 2.1 spec
参考： https://www.e-learn.cn/content/wangluowenzhang/2219061