Add support for Consumer Create Action

src/main/java/io/nats/client/JetStreamManagement.java

@@ -121,6 +121,28 @@ public interface JetStreamManagement {
      */
     ConsumerInfo addOrUpdateConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException;
 
+    /**
+     * Creates a consumer. Must not already exist.
+     * @param streamName name of the stream
+     * @param config the consumer configuration to use.
+     * @return consumer information.
+     * @throws IOException covers various communication issues with the NATS
+     *         server such as timeout or interruption
+     * @throws JetStreamApiException the request had an error related to the data such as the consumer already exists
+     */
+    ConsumerInfo createConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException;
+
+    /**
+     * Updates an existing consumer. Must already exist.
+     * @param streamName name of the stream
+     * @param config the consumer configuration to use.
+     * @return consumer information.
+     * @throws IOException covers various communication issues with the NATS
+     *         server such as timeout or interruption
+     * @throws JetStreamApiException the request had an error related to the data such as the consumer does not already exist
+     */
+    ConsumerInfo updateConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException;
+
     /**
      * Deletes a consumer.
      * @param streamName name of the stream

src/main/java/io/nats/client/api/ConsumerCreateRequest.java

@@ -16,20 +16,39 @@
 import io.nats.client.support.JsonSerializable;
 import io.nats.client.support.JsonUtils;
 
-import static io.nats.client.support.ApiConstants.CONFIG;
-import static io.nats.client.support.ApiConstants.STREAM_NAME;
+import static io.nats.client.support.ApiConstants.*;
 import static io.nats.client.support.JsonUtils.*;
 
 /**
  * Object used to make a request to create a consumer. Used Internally
  */
 public class ConsumerCreateRequest implements JsonSerializable {
+    public enum Action {
+        Create("create"),
+        Update("update"),
+        CreateOrUpdate(null);
+
+        public final String actionText;
+
+        Action(String actionText) {
+            this.actionText = actionText;
+        }
+    }
+
     private final String streamName;
     private final ConsumerConfiguration config;
+    private final Action action;
 
     public ConsumerCreateRequest(String streamName, ConsumerConfiguration config) {
         this.streamName = streamName;
         this.config = config;
+        this.action = Action.CreateOrUpdate;
+    }
+
+    public ConsumerCreateRequest(String streamName, ConsumerConfiguration config, Action action) {
+        this.streamName = streamName;
+        this.config = config;
+        this.action = action;
     }
 
     public String getStreamName() {
@@ -40,11 +59,16 @@ public ConsumerConfiguration getConfig() {
         return config;
     }
 
+    public Action getAction() {
+        return action;
+    }
+
     @Override
     public String toJson() {
         StringBuilder sb = beginJson();
 
         addField(sb, STREAM_NAME, streamName);
+        JsonUtils.addField(sb, ACTION, action.actionText);
         JsonUtils.addField(sb, CONFIG, config);
 
         return endJson(sb).toString();

src/main/java/io/nats/client/impl/NatsJetStreamImpl.java

@@ -81,7 +81,7 @@ ConsumerInfo _getConsumerInfo(String streamName, String consumerName) throws IOE
         return new ConsumerInfo(resp).throwOnHasError();
     }
 
-    ConsumerInfo _createConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException {
+    ConsumerInfo _createConsumer(String streamName, ConsumerConfiguration config, ConsumerCreateRequest.Action action) throws IOException, JetStreamApiException {
         // ConsumerConfiguration validates that name and durable are the same if both are supplied.
         String consumerName = config.getName();
         if (consumerName != null && !consumerCreate290Available) {
@@ -118,14 +118,14 @@ else if (durable == null) {
             subj = String.format(JSAPI_DURABLE_CREATE, streamName, durable);
         }
 
-        ConsumerCreateRequest ccr = new ConsumerCreateRequest(streamName, config);
+        ConsumerCreateRequest ccr = new ConsumerCreateRequest(streamName, config, action);
         Message resp = makeRequestResponseRequired(subj, ccr.serialize(), jso.getRequestTimeout());
         return new ConsumerInfo(resp).throwOnHasError();
     }
 
     void _createConsumerUnsubscribeOnException(String stream, ConsumerConfiguration cc, NatsJetStreamSubscription sub) throws IOException, JetStreamApiException {
         try {
-            ConsumerInfo ci = _createConsumer(stream, cc);
+            ConsumerInfo ci = _createConsumer(stream, cc, ConsumerCreateRequest.Action.CreateOrUpdate);
             sub.setConsumerName(ci.getName());
         }
         catch (IOException | JetStreamApiException e) {

src/main/java/io/nats/client/impl/NatsJetStreamManagement.java

@@ -128,7 +128,27 @@ public PurgeResponse purgeStream(String streamName, PurgeOptions options) throws
     public ConsumerInfo addOrUpdateConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException {
         validateStreamName(streamName, true);
         validateNotNull(config, "Config");
-        return _createConsumer(streamName, config);
+        return _createConsumer(streamName, config, ConsumerCreateRequest.Action.CreateOrUpdate);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public ConsumerInfo createConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException {
+        validateStreamName(streamName, true);
+        validateNotNull(config, "Config");
+        return _createConsumer(streamName, config, ConsumerCreateRequest.Action.Create);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public ConsumerInfo updateConsumer(String streamName, ConsumerConfiguration config) throws IOException, JetStreamApiException {
+        validateStreamName(streamName, true);
+        validateNotNull(config, "Config");
+        return _createConsumer(streamName, config, ConsumerCreateRequest.Action.Update);
     }
 
     /**

src/main/java/io/nats/client/impl/OrderedMessageManager.java

@@ -17,6 +17,7 @@
 import io.nats.client.Message;
 import io.nats.client.SubscribeOptions;
 import io.nats.client.api.ConsumerConfiguration;
+import io.nats.client.api.ConsumerCreateRequest;
 import io.nats.client.api.ConsumerInfo;
 
 import java.util.concurrent.atomic.AtomicReference;
@@ -98,7 +99,7 @@ private void handleErrorCondition() {
             // 3. make a new consumer using the same deliver subject but
             //    with a new starting point
             ConsumerConfiguration userCC = js.consumerConfigurationForOrdered(originalCc, lastStreamSeq, newDeliverSubject, actualConsumerName, null);
-            ConsumerInfo ci = js._createConsumer(stream, userCC); // this can fail when a server is down.
+            ConsumerInfo ci = js._createConsumer(stream, userCC, ConsumerCreateRequest.Action.Create); // this can fail when a server is down.
             sub.setConsumerName(ci.getName());
 
             // 4. restart the manager.

src/main/java/io/nats/client/support/ApiConstants.java

@@ -18,6 +18,7 @@ public interface ApiConstants {
     String ACK_FLOOR         = "ack_floor";
     String ACK_POLICY        = "ack_policy";
     String ACK_WAIT          = "ack_wait";
+    String ACTION            = "action";
     String ACTIVE            = "active";
     String ALLOW_ROLLUP_HDRS = "allow_rollup_hdrs";
     String ALLOW_DIRECT      = "allow_direct";