List<AMCRegistration> customers = new ArrayList<>();
customers.add(myReg);

Client client = ClientBuilder.newClient();

HttpAuthenticationFeature feature = HttpAuthenticationFeature.basic("user", "pass");
client.register(feature);
WebTarget target = client.target("https://foosvc.foo.org/api/amc");
target = target.path("PostFOO");
// Exception thrown here
String postResponse = target.request(MediaType.APPLICATION_JSON)
                .post(Entity.entity(customers, MediaType.APPLICATION_JSON),String.class);

Apr 16, 2021 11:29:02 AM org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor aroundWriteTo
SEVERE: MessageBodyWriter not found for media type=application/json, type=class java.util.ArrayList, genericType=class java.util.ArrayList.
Exception in thread "main" org.glassfish.jersey.message.internal.MessageBodyProviderNotFoundException: MessageBodyWriter not found for media type=application/json, type=class java.util.ArrayList, genericType=class java.util.ArrayList.

<dependency>
	<groupId>org.glassfish.jersey.media</groupId>
	<artifactId>jersey-media-moxy</artifactId>
</dependency>		

Client client = ClientBuilder
   .newBuilder()
    .property(LoggingFeature.LOGGING_FEATURE_VERBOSITY_CLIENT, LoggingFeature.Verbosity.PAYLOAD_ANY)
     .property(LoggingFeature.LOGGING_FEATURE_LOGGER_LEVEL_CLIENT, "INFO")
    .build();

<dependency>
	<groupId>org.glassfish.jersey.media</groupId>
	<artifactId>jersey-media-json-jackson</artifactId>
</dependency>