NIFI-3799 Add Input Requirement Info to Docs

Added input requirement info for processor documentation

This closes #1756.

Signed-off-by: James Wing <jvwing@gmail.com>

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-documentation/src/main/java/org/apache/nifi/documentation/html/HtmlDocumentationWriter.java

@@ -18,6 +18,7 @@ package org.apache.nifi.documentation.html;
 
 import org.apache.nifi.annotation.behavior.DynamicProperties;
 import org.apache.nifi.annotation.behavior.DynamicProperty;
+import org.apache.nifi.annotation.behavior.InputRequirement;
 import org.apache.nifi.annotation.behavior.Restricted;
 import org.apache.nifi.annotation.behavior.Stateful;
 import org.apache.nifi.annotation.documentation.CapabilityDescription;
@@ -146,6 +147,7 @@ public class HtmlDocumentationWriter implements DocumentationWriter {
         writeAdditionalBodyInfo(configurableComponent, xmlStreamWriter);
         writeStatefulInfo(configurableComponent, xmlStreamWriter);
         writeRestrictedInfo(configurableComponent, xmlStreamWriter);
+        writeInputRequirementInfo(configurableComponent, xmlStreamWriter);
         writeSeeAlso(configurableComponent, xmlStreamWriter);
         xmlStreamWriter.writeEndElement();
     }
@@ -167,6 +169,37 @@ public class HtmlDocumentationWriter implements DocumentationWriter {
         xmlStreamWriter.writeEndElement();
     }
 
+    /**
+     * Add in the documentation information regarding the component whether it accepts an
+     * incoming relationship or not.
+     *
+     * @param configurableComponent the component to describe
+     * @param xmlStreamWriter the stream writer to use
+     * @throws XMLStreamException thrown if there was a problem writing the XML
+     */
+    private void writeInputRequirementInfo(ConfigurableComponent configurableComponent, XMLStreamWriter xmlStreamWriter)
+            throws XMLStreamException {
+        final InputRequirement inputRequirement = configurableComponent.getClass().getAnnotation(InputRequirement.class);
+
+        if(inputRequirement != null) {
+            writeSimpleElement(xmlStreamWriter, "h3", "Input requirement: ");
+            switch (inputRequirement.value()) {
+                case INPUT_FORBIDDEN:
+                    xmlStreamWriter.writeCharacters("This component does not allow an incoming relationship.");
+                    break;
+                case INPUT_ALLOWED:
+                    xmlStreamWriter.writeCharacters("This component allows an incoming relationship.");
+                    break;
+                case INPUT_REQUIRED:
+                    xmlStreamWriter.writeCharacters("This component requires an incoming relationship.");
+                    break;
+                default:
+                    xmlStreamWriter.writeCharacters("This component does not have input requirement.");
+                    break;
+            }
+        }
+    }
+
     /**
      * Write the description of the Stateful annotation if provided in this component.
      *

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-documentation/src/test/java/org/apache/nifi/documentation/example/FullyDocumentedProcessor.java

@@ -18,11 +18,13 @@ package org.apache.nifi.documentation.example;
 
 import org.apache.nifi.annotation.behavior.DynamicProperty;
 import org.apache.nifi.annotation.behavior.DynamicRelationship;
+import org.apache.nifi.annotation.behavior.InputRequirement;
 import org.apache.nifi.annotation.behavior.ReadsAttribute;
 import org.apache.nifi.annotation.behavior.Restricted;
 import org.apache.nifi.annotation.behavior.Stateful;
 import org.apache.nifi.annotation.behavior.WritesAttribute;
 import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
 import org.apache.nifi.annotation.documentation.CapabilityDescription;
 import org.apache.nifi.annotation.documentation.SeeAlso;
 import org.apache.nifi.annotation.documentation.Tags;
@@ -56,6 +58,7 @@ import java.util.Set;
 @DynamicRelationship(name = "name from dynamic property", description = "all files that match the properties XPath")
 @Stateful(scopes = {Scope.CLUSTER, Scope.LOCAL}, description = "state management description")
 @Restricted("processor restriction description")
+@InputRequirement(Requirement.INPUT_FORBIDDEN)
 public class FullyDocumentedProcessor extends AbstractProcessor {
 
     public static final PropertyDescriptor DIRECTORY = new PropertyDescriptor.Builder().name("Input Directory")

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-documentation/src/test/java/org/apache/nifi/documentation/html/ProcessorDocumentationWriterTest.java

@@ -81,6 +81,9 @@ public class ProcessorDocumentationWriterTest {
         assertNotContains(results, "No tags provided.");
         assertNotContains(results, "Additional Details...");
 
+        // input requirement
+        assertContains(results, "This component does not allow an incoming relationship.");
+
         // verify the right OnRemoved and OnShutdown methods were called
         Assert.assertEquals(0, processor.getOnRemovedArgs());
         Assert.assertEquals(0, processor.getOnRemovedNoArgs());
@@ -122,6 +125,9 @@ public class ProcessorDocumentationWriterTest {
 
         // state management
         assertContains(results, "This component is not restricted.");
+
+        // input requirement
+        assertNotContains(results, "Input requirement:");
     }
 
     @Test