optimize set content-type for save state

Signed-off-by: theonefx <chenxilzx1@gmail.com>

Author: theonefx

sdk/src/main/java/io/dapr/client/AbstractDaprClient.java

@@ -501,11 +501,7 @@ public Mono<Void> saveState(String storeName, String key, Object value) {
    */
   @Override
   public Mono<Void> saveState(String storeName, String key, String etag, Object value, StateOptions options) {
-    Map<String, String> meta = null;
-    if (value != null) {
-      meta = Collections.singletonMap("contentType", stateSerializer.getContentType());
-    }
-    State<?> state = new State<>(key, value, etag, meta, options);
+    State<?> state = new State<>(key, value, etag, null, options);
     return this.saveBulkState(storeName, Collections.singletonList(state));
   }
 

sdk/src/main/java/io/dapr/client/DaprClientImpl.java

@@ -825,6 +825,9 @@ private <T> CommonProtos.StateItem.Builder buildStateRequest(State<T> state) thr
     if (state.getMetadata() != null) {
       stateBuilder.putAllMetadata(state.getMetadata());
     }
+    if (objectSerializer.getContentType() != null && !objectSerializer.getContentType().isEmpty()) {
+      stateBuilder.putMetadata(io.dapr.client.domain.Metadata.CONTENT_TYPE, objectSerializer.getContentType());
+    }
     if (bytes != null) {
       stateBuilder.setValue(ByteString.copyFrom(bytes));
     }