If you compile your code with java 8 and any new java 8 language feature deployment will fail as jandex won't be able to index classes.

18:36:17,431 WARN  [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015852: Could not index class com/prosper/document/ws/impl/DownloadCSVEndpointImpl.class at /C:/java/jboss-eap-6.3/standalone/deployments/core-document.war/WEB-INF/classes: java.lang.IllegalStateException: Unknown tag! pos=32 poolCount = 155
       at org.jboss.jandex.Indexer.processConstantPool(Indexer.java:606) [jandex-1.0.3.Final-redhat-2.jar:1.0.3.Final-redhat-2]
       at org.jboss.jandex.Indexer.index(Indexer.java:640) [jandex-1.0.3.Final-redhat-2.jar:1.0.3.Final-redhat-2]
       at org.jboss.as.server.deployment.annotation.ResourceRootIndexer.indexResourceRoot(ResourceRootIndexer.java:100) [jboss-as-server-7.4.0.Final-redhat-19.jar:7.4.0.Final-redhat-19]
       at org.jboss.as.server.deployment.annotation.AnnotationIndexProcessor.deploy(AnnotationIndexProcessor.java:51) [jboss-as-server-7.4.0.Final-redhat-19.jar:7.4.0.Final-redhat-19]
       at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:159) [jboss-as-server-7.4.0.Final-redhat-19.jar:7.4.0.Final-redhat-19]
       at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1980) [jboss-msc-1.1.5.Final-redhat-1.jar:1.1.5.Final-redhat-1]
       at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1913) [jboss-msc-1.1.5.Final-redhat-1.jar:1.1.5.Final-redhat-1]
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [rt.jar:1.8.0_25]
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [rt.jar:1.8.0_25]
       at java.lang.Thread.run(Thread.java:745) [rt.jar:1.8.0_25]