RESTEasy client can't find JSON provider in an application deployed in JBoss EAP 6.x

Issue

• Having an application that contains a servlet that uses RESTEasy client and the Proxy class to create a client based on my JAX-RS interface:

When reaching it, seems that the JSON built in provider isn't found and the error below is thrown:

org.jboss.resteasy.client.exception.ResteasyClientException: Unexpected exception type
    org.jboss.resteasy.client.exception.mapper.ApacheHttpClient4ExceptionMapper.toException(ApacheHttpClient4ExceptionMapper.java:73)
    org.jboss.resteasy.client.exception.mapper.ApacheHttpClient4ExceptionMapper.toException(ApacheHttpClient4ExceptionMapper.java:59)
    org.jboss.resteasy.client.core.ClientInvoker.invoke(ClientInvoker.java:118)
    org.jboss.resteasy.client.core.ClientProxy.invoke(ClientProxy.java:88)
    $Proxy113.test(Unknown Source)
    com.abc.MyServlet.doGet(MyServlet.java:48)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
JBWEB000071: root cause

java.lang.RuntimeException: could not find writer for content-type application/json type: com.abc.MyJaxRsInterface
    org.jboss.resteasy.client.ClientRequest.writeRequestBody(ClientRequest.java:469)
    org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor.writeRequestBodyToOutputStream(ApacheHttpClient4Executor.java:393)
    org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor.buildEntity(ApacheHttpClient4Executor.java:360)
    org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor.loadHttpMethod(ApacheHttpClient4Executor.java:332)
    org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor.execute(ApacheHttpClient4Executor.java:180)
    org.jboss.resteasy.core.interception.ClientExecutionContextImpl.proceed(ClientExecutionContextImpl.java:39)
    org.jboss.resteasy.plugins.interceptors.encoding.AcceptEncodingGZIPInterceptor.execute(AcceptEncodingGZIPInterceptor.java:40)
    org.jboss.resteasy.core.interception.ClientExecutionContextImpl.proceed(ClientExecutionContextImpl.java:45)
    org.jboss.resteasy.client.ClientRequest.execute(ClientRequest.java:443)
    org.jboss.resteasy.client.ClientRequest.httpMethod(ClientRequest.java:677)
    org.jboss.resteasy.client.core.ClientInvoker.invoke(ClientInvoker.java:111)
    org.jboss.resteasy.client.core.ClientProxy.invoke(ClientProxy.java:88)
    $Proxy113.test(Unknown Source)
    com.abc.MyServlet.doGet(MyServlet.java:48)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)

• But if accessing a JAX-RS application and then access the client, it will work. How to initialize RESTEasy built in JSON provider?