Handle OkHttp POST with empty body

src/main/java/io/github/sashirestela/cleverclient/client/OkHttpClientAdapter.java

@@ -140,7 +140,7 @@ private FunctionsByCategory getFunctions(ReturnType returnType) {
     }
 
     private Request convertToOkHttpRequest(RequestData request) {
-        var requestBody = createRequestBody(request.getBody(), request.getContentType());
+        var requestBody = createRequestBody(request.getBody(), request.getContentType(), request.getHttpMethod());
         var headersArray = request.getHeaders().toArray(new String[0]);
         var requestBuilder = new Request.Builder()
                 .url(request.getUrl())
@@ -152,10 +152,13 @@ private Request convertToOkHttpRequest(RequestData request) {
     }
 
     @SuppressWarnings("unchecked")
-    private RequestBody createRequestBody(Object bodyObject, ContentType contentType) {
+    private RequestBody createRequestBody(Object bodyObject, ContentType contentType, String httpMethod) {
         RequestBody requestBody = null;
         if (contentType == null) {
             logger.debug(REQUEST_BODY_FORMAT, "(Empty)");
+            if (httpMethod.equalsIgnoreCase("POST")) {
+                requestBody = RequestBody.create("", null);
+            }
         } else if (contentType == ContentType.MULTIPART_FORMDATA) {
             logger.debug(REQUEST_BODY_FORMAT, bodyObject);
             var bodyBytes = HttpMultipart.toByteArrays((Map<String, Object>) bodyObject);

src/test/java/io/github/sashirestela/cleverclient/http/HttpProcessorTest.java

@@ -390,6 +390,28 @@ default void shouldShutdownWithoutExceptions() {
         testShutdown();
     }
 
+    @Test
+    default void shouldReturnAnObjectSyncWhenIsPostMethodAndBodyIsEmpty() throws IOException, InterruptedException {
+        setMocksForString(SyncType.SYNC, "{\"id\":100,\"description\":\"Description\",\"active\":true}");
+
+        var service = getHttpProcessor().createProxy(ITest.SyncService.class);
+        var actualDemo = service.cancelDemo(100);
+        var expectedDemo = new ITest.Demo(100, "Description", true);
+
+        assertEquals(expectedDemo, actualDemo);
+    }
+
+    @Test
+    default void shouldReturnAnObjectAsyncWhenIsPostMethodAndBodyIsEmpty() throws IOException, InterruptedException {
+        setMocksForString(SyncType.ASYNC, "{\"id\":100,\"description\":\"Description\",\"active\":true}");
+
+        var service = getHttpProcessor().createProxy(ITest.AsyncService.class);
+        var actualDemo = service.cancelDemo(100).join();
+        var expectedDemo = new ITest.Demo(100, "Description", true);
+
+        assertEquals(expectedDemo, actualDemo);
+    }
+
     private String transformUsers(String jsonInput) {
         List<String> flatUsers = new ArrayList<>();
         String patternStr = "\"id\":\\s*(\\d+).*?" + // id

src/test/java/io/github/sashirestela/cleverclient/http/ITest.java

@@ -75,6 +75,9 @@ interface AsyncService {
         @GET("/{demoId}")
         CompletableFuture<Demo> getDemo(@Path("demoId") Integer demoId);
 
+        @POST
+        CompletableFuture<Demo> cancelDemo(@Path("demoId") Integer demoId);
+
         @GET("/{genericDemoId}")
         CompletableFuture<Generic<Demo>> getGenericDemo(@Path("genericDemoId") Integer genericDemoId);
 
@@ -113,6 +116,9 @@ interface SyncService {
         @GET("/{demoId}")
         Demo getDemo(@Path("demoId") Integer demoId);
 
+        @POST
+        Demo cancelDemo(@Path("demoId") Integer demoId);
+
         @GET("/{genericDemoId}")
         Generic<Demo> getGenericDemo(@Path("genericDemoId") Integer genericDemoId);