NIFI-1620 Allow empty Content-Type in InvokeHTTP processor

This closes #272.

Signed-off-by: Aldrin Piri <aldrin@apache.org>

nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/InvokeHTTP.java

@@ -221,7 +221,16 @@ public final class InvokeHTTP extends AbstractProcessor {
         .required(true)
         .expressionLanguageSupported(true)
         .defaultValue("${" + CoreAttributes.MIME_TYPE.key() + "}")
-        .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+        .addValidator(StandardValidators.createAttributeExpressionLanguageValidator(AttributeExpression.ResultType.STRING))
+        .build();
+
+    public static final PropertyDescriptor PROP_SEND_BODY = new PropertyDescriptor.Builder()
+            .name("send-message-body")
+            .displayName("Send Message Body")
+            .description("If true, sends the HTTP message body on POST/PUT requests (default).  If false, suppresses the message body and content-type header for these requests.")
+            .defaultValue("true")
+            .allowableValues("true", "false")
+            .required(false)
             .build();
 
     // Per RFC 7235, 2617, and 2616.
@@ -347,6 +356,7 @@ public final class InvokeHTTP extends AbstractProcessor {
             PROP_TRUSTED_HOSTNAME,
             PROP_ADD_HEADERS_TO_REQUEST,
             PROP_CONTENT_TYPE,
+            PROP_SEND_BODY,
             PROP_USE_CHUNKED_ENCODING,
             PROP_PENALIZE_NO_RETRY));
 
@@ -761,6 +771,7 @@ public final class InvokeHTTP extends AbstractProcessor {
     }
 
     private RequestBody getRequestBodyToSend(final ProcessSession session, final ProcessContext context, final FlowFile requestFlowFile) {
+        if(context.getProperty(PROP_SEND_BODY).asBoolean()) {
             return new RequestBody() {
                 @Override
                 public MediaType contentType() {
@@ -779,6 +790,9 @@ public final class InvokeHTTP extends AbstractProcessor {
                     return useChunked ? -1 : requestFlowFile.getSize();
                 }
             };
+        } else {
+            return RequestBody.create(null, new byte[0]);
+        }
     }
 
     private Request.Builder setHeaderProperties(final ProcessContext context, Request.Builder requestBuilder, final FlowFile requestFlowFile) {

nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/util/TestInvokeHttpCommon.java

@@ -978,6 +978,26 @@ public abstract class TestInvokeHttpCommon {
         runner.assertTransferCount(InvokeHTTP.REL_RESPONSE, 1);
     }
 
+    @Test
+    public void testPostWithEmptyBodySet() throws Exception {
+        final String suppliedMimeType = "";
+        addHandler(new MutativeMethodHandler(MutativeMethod.POST, suppliedMimeType));
+
+        runner.setNonLoopConnection(false);
+        runner.setProperty(InvokeHTTP.PROP_METHOD, "POST");
+        runner.setProperty(InvokeHTTP.PROP_URL, url + "/post");
+        runner.setProperty(InvokeHTTP.PROP_CONTENT_TYPE, suppliedMimeType);
+        runner.setProperty(InvokeHTTP.PROP_SEND_BODY, "false");
+
+        final Map<String, String> attrs = new HashMap<>();
+        attrs.put(CoreAttributes.MIME_TYPE.key(), suppliedMimeType);
+        runner.enqueue("Hello".getBytes(), attrs);
+
+        runner.run(1);
+        runner.assertTransferCount(InvokeHTTP.REL_SUCCESS_REQ, 1);
+        runner.assertTransferCount(InvokeHTTP.REL_RESPONSE, 1);
+    }
+
     @Test
     public void testPutWithMimeType() throws Exception {
         final String suppliedMimeType = "text/plain";
@@ -1385,10 +1405,20 @@ public abstract class TestInvokeHttpCommon {
             baseRequest.setHandled(true);
 
             if(method.name().equals(request.getMethod())) {
+                if(this.expectedContentType.isEmpty()) {
+                    Assert.assertNull(request.getHeader("Content-Type"));
+                } else {
                     assertEquals(this.expectedContentType,request.getHeader("Content-Type"));
+                }
+
                 final String body = request.getReader().readLine();
                 this.trackedHeaderValue = baseRequest.getHttpFields().get(headerToTrack);
+
+                if(this.expectedContentType.isEmpty()) {
+                    Assert.assertNull(body);
+                } else {
                     assertEquals("Hello", body);
+                }
             } else {
                 response.setStatus(404);
                 response.setContentType("text/plain");