Environment (Required on creation):

• Tomcat (standalone and non-standalone webapp)

Description (Required on creation; please attach any relevant screenshots, stacktraces, log files, etc. to the ticket):

• Cannot use webapps

Steps to reproduce (Required on creation):

• Start Tomcat distro
• Go to webapp login page

Observed Behavior (Required on creation):

• An error is displayed
• Login is not possible
• localhost.log shows

  28-Jan-2021 15:03:27.306 SCHWERWIEGEND [http-nio-8080-exec-5] org.apache.catalina.core.ApplicationContext.log Servlet.init() for servlet [Admin Api] threw exception
  	java.lang.NoSuchFieldError: SERVER_SENT_EVENTS_TYPE
  		at org.jboss.resteasy.core.ResourceMethodInvoker.isSseResourceMethod(ResourceMethodInvoker.java:184)
  		at org.jboss.resteasy.core.ResourceMethodInvoker.<init>(ResourceMethodInvoker.java:169)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.processMethod(ResourceMethodRegistry.java:355)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.register(ResourceMethodRegistry.java:278)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:229)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:201)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:187)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.addResourceFactory(ResourceMethodRegistry.java:164)
  		at org.jboss.resteasy.core.ResourceMethodRegistry.addPerRequestResource(ResourceMethodRegistry.java:81)
  		at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:517)
  		at org.jboss.resteasy.spi.ResteasyDeployment.startInternal(ResteasyDeployment.java:288)
  		at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:93)
  		at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:140)
  		at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:42)
  		at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1134)
  		at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1089)
  		at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:761)
  		at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
  		at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
  		at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
  		at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
  		at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
  		at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
  		at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
  		at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
  		at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
  		at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
  		at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:888)
  		at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597)
  		at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
  		at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  		at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  		at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  		at java.lang.Thread.run(Thread.java:748)
  

Expected behavior (Required on creation):

• Webapp use is possible

Root Cause (Required on prioritization):

• Tomcat webapp has both JAX-RS 2.0 and JAX-RS 2.1 API on the classpath
• The current Resteasy version requires 2.1
• Depending on which classes are loaded first

Solution Ideas (Optional):

• Make sure we only include one JAX-RS API Jar
• Check other distros
• Apply this commit on 7.12: https://github.com/camunda/camunda-bpm-platform-ee-maintenance/commit/df7d2f096df360c3112ce014f8dc7879bbec486d#diff-1aca71d8ab0258c2025e7b338eb601f6d3fb367d5f6e461a9a7a48694d682d10

Hints (Optional):

Distro assessment

Tomcat:

• it's correct in the non-EE webapp

Wildfly/JBoss:

• does not contain JAX-RS implementation

WLS

• does not contain JAX-RS implementation

WAS 8

• does not contain JAX-RS implementation

WAS 9

• Uses Jersey

Run

• doesn't exist in 7.12
• uses Jersey