"Arguments must not be null" when sending a null JSON object with ResteasyWebTarget ----------------------------------------------------------------------------------- Key: WFLY-9041 URL: https://issues.jboss.org/browse/WFLY-9041 Project: WildFly Issue Type: Bug Components: REST Affects Versions: 11.0.0.Alpha1 Reporter: Chao Wang Assignee: Alessio Soldano Having a very simple WS application with a REST endpoint that consumes a JSON object: {code:java} @Path("hello") public class HelloWorld { @POST @Path("entity") @Produces({MediaType.APPLICATION_JSON}) @Consumes({MediaType.APPLICATION_JSON}) public Greeting helloEntity(Greeter greeter) { return new Greeting(greeter); } } {code} If the resteasy-client with the the _ResteasyWebTarget_ proxy is used: {code:java} System.out.println( ((ResteasyWebTarget) ClientBuilder.newClient() .target("http://jboss.sample.com:8080") .path("resteasy-test") .path("ws") .path("hello")) .proxy(HelloWorldInterface.class) .helloEntity(null)); {code} The following exception is thrown at client side (no data is sent): {code} java.lang.IllegalArgumentException: Arguments must not be null. at javax.ws.rs.core.GenericEntity.<init>(GenericEntity.java:148) at org.jboss.resteasy.client.jaxrs.internal.proxy.processors.invocation.MessageBodyParameterProcessor.process(MessageBodyParameterProcessor.java:35) at org.jboss.resteasy.client.jaxrs.internal.proxy.ClientInvoker.createRequest(ClientInvoker.java:135) at org.jboss.resteasy.client.jaxrs.internal.proxy.ClientInvoker.invoke(ClientInvoker.java:101) at org.jboss.resteasy.client.jaxrs.internal.proxy.ClientProxy.invoke(ClientProxy.java:64) at com.sun.proxy.$Proxy39.helloEntity(Unknown Source) at com.redhat.sample.test.Client.main(Client.java:63) {code} You can send a null using the standard jax-rs methods: {code:java} System.out.println(ClientBuilder.newClient() .target("http://jboss.sample.com:8080") .path("resteasy-test") .path("ws") .path("hello") .path("entity") .request(MediaType.APPLICATION_JSON) .accept(MediaType.APPLICATION_JSON) .post(Entity.entity(null, MediaType.APPLICATION_JSON)) .readEntity(Greeting.class)); {code}