Inject jax InjectAdapter helper class.

Author: Andrew Kent

dd-java-agent/instrumentation/jax-rs-client/src/main/java/datadog/trace/instrumentation/jaxrs/JaxRsClientInstrumentation.java

@@ -33,7 +33,8 @@ protected AgentBuilder apply(final AgentBuilder agentBuilder) {
         .transform(
             new HelperInjector(
                 "datadog.trace.instrumentation.jaxrs.ClientTracingFeature",
-                "datadog.trace.instrumentation.jaxrs.ClientTracingFilter"))
+                "datadog.trace.instrumentation.jaxrs.ClientTracingFilter",
+                "datadog.trace.instrumentation.jaxrs.InjectAdapter"))
         .transform(DDTransformers.defaultTransformers())
         .transform(
             DDAdvice.create()