added test to verify usage of correct converter

application/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java

@@ -27,6 +27,10 @@ import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.List;
 
+/**
+ * RestTemplate firstly uses MappingJackson2XmlHttpMessageConverter converter instead of MappingJackson2HttpMessageConverter.
+ * It produces error UnsupportedMediaType, so this converter had to be shadowed for read and write operations to use the correct converter
+ */
 public class MappingJackson2XmlHttpMessageConverter extends AbstractJackson2HttpMessageConverter {
     private static final List<MediaType> problemDetailMediaTypes;
 

application/src/test/java/org/thingsboard/server/system/RestTemplateConvertersTest.java

@@ -0,0 +1,61 @@
+/**
+ * Copyright © 2016-2024 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.server.system;
+
+import lombok.extern.slf4j.Slf4j;
+import org.junit.Test;
+import org.springframework.http.MediaType;
+import org.springframework.mock.http.client.MockClientHttpRequest;
+import org.springframework.test.web.client.MockRestServiceServer;
+import org.springframework.util.ClassUtils;
+import org.springframework.web.client.RestTemplate;
+
+import java.nio.charset.StandardCharsets;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
+import static org.springframework.test.web.client.response.MockRestResponseCreators.withSuccess;
+
+
+@Slf4j
+public class RestTemplateConvertersTest {
+
+    @Test
+    public void testMappingJackson2HttpMessageConverterIsUsedInsteadOfMappingJackson2XmlHttpMessageConverter() {
+        ClassLoader classLoader = RestTemplate.class.getClassLoader();
+        boolean jackson2XmlPresent = ClassUtils.isPresent("com.fasterxml.jackson.dataformat.xml.XmlMapper", classLoader);
+        assertThat(jackson2XmlPresent).isTrue();
+
+        RestTemplate restTemplate = new RestTemplate();
+        MockRestServiceServer mockServer = MockRestServiceServer.createServer(restTemplate);
+        mockServer.expect(requestTo("/test"))
+                .andExpect(request -> {
+                    MockClientHttpRequest mockRequest = (MockClientHttpRequest) request;
+                    byte[] body = mockRequest.getBodyAsBytes();
+                    String requestBody = new String(body, StandardCharsets.UTF_8);
+                    assertThat(requestBody).contains("{\"name\":\"test\",\"value\":1}");
+                })
+                .andRespond(withSuccess("{\"name\":\"test\",\"value\":1}", MediaType.APPLICATION_JSON));
+
+        TestObject requestObject = new TestObject("test", 1);
+        TestObject actualObject = restTemplate.postForObject("/test", requestObject, TestObject.class);
+        assertThat(actualObject).isEqualTo(requestObject);
+        mockServer.verify();
+    }
+
+    record TestObject(String name, int value) {}
+
+}