diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
index a10302b183df..48c9d986bb53 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
@@ -874,9 +874,17 @@ public class ApiClient {
     } else {
       // We let jersey handle the serialization
       if (isBodyNullable) { // payload is nullable
-        entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "null" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        }
       } else {
-        entity = Entity.entity(obj == null ? "" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "" : obj, contentType);
+        }
       }
     }
     return entity;
@@ -911,7 +919,7 @@ public class ApiClient {
         if (isBodyNullable) {
           return obj == null ? "null" : json.getMapper().writeValueAsString(obj);
         } else {
-          return json.getMapper().writeValueAsString(obj);
+          return obj == null ? "" : json.getMapper().writeValueAsString(obj);
         }
       }
     } catch (Exception ex) {
diff --git a/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
index a8ce193dc362..a0529ef23392 100644
--- a/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
@@ -791,9 +791,17 @@ public Entity<?> serialize(Object obj, Map<String, Object> formParams, String co
     } else {
       // We let jersey handle the serialization
       if (isBodyNullable) { // payload is nullable
-        entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "null" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        }
       } else {
-        entity = Entity.entity(obj == null ? "" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "" : obj, contentType);
+        }
       }
     }
     return entity;
@@ -828,7 +836,7 @@ public String serializeToString(Object obj, Map<String, Object> formParams, Stri
         if (isBodyNullable) {
           return obj == null ? "null" : json.getMapper().writeValueAsString(obj);
         } else {
-          return json.getMapper().writeValueAsString(obj);
+          return obj == null ? "" : json.getMapper().writeValueAsString(obj);
         }
       }
     } catch (Exception ex) {
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
index 2e37397e8ab7..af327d787786 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
@@ -870,9 +870,17 @@ public Entity<?> serialize(Object obj, Map<String, Object> formParams, String co
     } else {
       // We let jersey handle the serialization
       if (isBodyNullable) { // payload is nullable
-        entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "null" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "null" : obj, contentType);
+        }
       } else {
-        entity = Entity.entity(obj == null ? "" : obj, contentType);
+        if (obj instanceof String) {
+          entity = Entity.entity(obj == null ? "" : "\"" + ((String)obj).replaceAll("\"", Matcher.quoteReplacement("\\\"")) + "\"", contentType);
+        } else {
+          entity = Entity.entity(obj == null ? "" : obj, contentType);
+        }
       }
     }
     return entity;
@@ -907,7 +915,7 @@ public String serializeToString(Object obj, Map<String, Object> formParams, Stri
         if (isBodyNullable) {
           return obj == null ? "null" : json.getMapper().writeValueAsString(obj);
         } else {
-          return json.getMapper().writeValueAsString(obj);
+          return obj == null ? "" : json.getMapper().writeValueAsString(obj);
         }
       }
     } catch (Exception ex) {
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8/src/test/java/org/openapitools/client/ApiClientTest.java b/samples/openapi3/client/petstore/java/jersey2-java8/src/test/java/org/openapitools/client/ApiClientTest.java
new file mode 100644
index 000000000000..fcccad7efba3
--- /dev/null
+++ b/samples/openapi3/client/petstore/java/jersey2-java8/src/test/java/org/openapitools/client/ApiClientTest.java
@@ -0,0 +1,64 @@
+package org.openapitools.client;
+
+import org.openapitools.client.model.*;
+import org.openapitools.client.ApiClient;
+
+import java.lang.Exception;
+import java.util.Arrays;
+import java.util.Date;
+import java.util.TimeZone;
+import java.text.SimpleDateFormat;
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import org.junit.*;
+import static org.junit.Assert.*;
+
+public class ApiClientTest {
+    ApiClient apiClient = null;
+    Pet pet = null;
+
+    @Before
+    public void setup() {
+        apiClient = new ApiClient();
+        pet = new Pet();
+    }
+
+    @Test
+    public void testSerializeToString() throws Exception {
+        Long petId = 4321L;
+        pet.setId(petId);
+        pet.setName("jersey2 java8 pet");
+        Category category = new Category();
+        category.setId(petId);
+        category.setName("jersey2 java8 category");
+        pet.setCategory(category);
+        pet.setStatus(Pet.StatusEnum.AVAILABLE);
+        pet.setPhotoUrls(Arrays.asList("A", "B", "C"));
+        Tag tag = new Tag();
+        tag.setId(petId);
+        tag.setName("jersey2 java8 tag");
+        pet.setTags(Arrays.asList(tag));
+
+        String result = "{\"id\":4321,\"category\":{\"id\":4321,\"name\":\"jersey2 java8 category\"},\"name\":\"jersey2 java8 pet\",\"photoUrls\":[\"A\",\"B\",\"C\"],\"tags\":[{\"id\":4321,\"name\":\"jersey2 java8 tag\"}],\"status\":\"available\"}";
+        assertEquals(result, apiClient.serializeToString(pet, null, "application/json", false));
+        // nulllable and there should be no diffencne as the payload is not null
+        assertEquals(result, apiClient.serializeToString(pet, null, "application/json", true));
+
+        // non-nullable null object should be converted to "" (empty body)
+        assertEquals("", apiClient.serializeToString(null, null, "application/json", false));
+        // nullable null object should be converted to "null"
+        assertEquals("null", apiClient.serializeToString(null, null, "application/json", true));
+
+        // non-nullable empty string should be converted to "\"\"" (empty json string)
+        assertEquals("\"\"", apiClient.serializeToString("", null, "application/json", false));
+        // nullable empty string should be converted to "\"\"" (empty json string)
+        assertEquals("\"\"", apiClient.serializeToString("", null, "application/json", true));
+
+        // non-nullable string "null" should be converted to "\"null\""
+        assertEquals("\"null\"", apiClient.serializeToString("null", null, "application/json", false));
+        // nullable string "null" should be converted to "\"null\""
+        assertEquals("\"null\"", apiClient.serializeToString("null", null, "application/json", true));
+    }
+
+}