When a Java 2 security manager is enabled, an AccessControlException is thrown while creating a new JAX-RS Client instance:

("java.util.PropertyPermission" "org.jboss.resteasy.max_mediatype_cache_size" "read")
{{Stack: }}
java.security.AccessControlException: Access denied ("java.util.PropertyPermission" "org.jboss.resteasy.max_mediatype_cache_size" "read")java.base/java.security.AccessController.throwACE(AccessController.java:176)
java.base/java.security.AccessController.checkPermissionHelper(AccessController.java:237)
java.base/java.security.AccessController.checkPermission(AccessController.java:373)
java.base/java.lang.SecurityManager.checkPermission(SecurityManager.java:322)
com.ibm.ws.kernel.launch.internal.MissingDoPrivDetectionSecurityManager.checkPermission(MissingDoPrivDetectionSecurityManager.java:45)
java.base/java.lang.SecurityManager.checkPropertyAccess(SecurityManager.java:1066)
java.base/java.lang.System.getProperty(System.java:450)
java.base/java.lang.System.getProperty(System.java:419)
java.base/java.lang.Integer.getInteger(Integer.java:1331)
java.base/java.lang.Integer.getInteger(Integer.java:1287)
org.jboss.resteasy.plugins.delegates.MediaTypeHeaderDelegate.<clinit>(MediaTypeHeaderDelegate.java:24)
org.jboss.resteasy.core.providerfactory.ResteasyProviderFactoryImpl.initializeCommon(ResteasyProviderFactoryImpl.java:224)
org.jboss.resteasy.core.providerfactory.ResteasyProviderFactoryImpl.<init>(ResteasyProviderFactoryImpl.java:152)
org.jboss.resteasy.plugins.providers.RegisterBuiltin$1.<init>(RegisterBuiltin.java:46)
org.jboss.resteasy.plugins.providers.RegisterBuiltin.getClientInitializedResteasyProviderFactory(RegisterBuiltin.java:46)
org.jboss.resteasy.client.jaxrs.internal.ResteasyClientBuilderImpl.getProviderFactory(ResteasyClientBuilderImpl.java:355)
org.jboss.resteasy.client.jaxrs.internal.ResteasyClientBuilderImpl.build(ResteasyClientBuilderImpl.java:373)
org.jboss.resteasy.client.jaxrs.internal.ResteasyClientBuilderImpl.build(ResteasyClientBuilderImpl.java:43)
javax.ws.rs.client.ClientBuilder.newClient(ClientBuilder.java:121)
com.ibm.ws.jaxrs21.fat.uriInfo.ClientTestServlet.init(ClientTestServlet.java:41)

It should be possible to avoid this by wrapping the System.getProperty(...) and Integer.getInteger(...) calls inside a doPriv block.