Fix for JavaTranslator handling of has with null last argument

CHANGELOG.asciidoc

@@ -138,6 +138,7 @@ This release also includes changes from <<release-3-7-XXX, 3.7.XXX>>.
 * Modified `limit()`, `skip()`, range()` in `repeat()` to track per-iteration counters.
 * Moved `Traverser` loop logic into new interface `NL_SL_Traverser` and changed loop-supporting `Traverser`s to extend the common interface.
 * Fixed `sample()` in `repeat()` computer algorithm to retain the configured sample size per loop
+* Fixed `JavaTranslator` to handle scenarios where the last argument to `has()` is null which previously could cause an exception.
 
 == TinkerPop 3.7.0 (Gremfir Master of the Pan Flute)
 

gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/jsr223/JavaTranslator.java

@@ -21,8 +21,8 @@
 
 import org.apache.commons.configuration2.BaseConfiguration;
 import org.apache.commons.configuration2.Configuration;
-import org.apache.commons.configuration2.MapConfiguration;
 import org.apache.tinkerpop.gremlin.process.traversal.Bytecode;
+import org.apache.tinkerpop.gremlin.process.traversal.P;
 import org.apache.tinkerpop.gremlin.process.traversal.Translator;
 import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
 import org.apache.tinkerpop.gremlin.process.traversal.TraversalSource;
@@ -301,8 +301,8 @@ private Object invokeMethod(final Object delegate, final Class<?> returnType, fi
                             }
                         }
 
-                        // special case has() where the first arg is null - sometimes this can end up with the T being
-                        // null and in 3.5.x that generates an exception which raises badly in the translator. it is
+                        // special cases of has() where the first or last arg is null - sometimes this can end up with the T or P being
+                        // null which generates an exception which raises badly in the translator. it is
                         // safer to force this to the String form by letting this "found" version pass. In java this
                         // form of GraphTraversal can't be produced because of validations for has(T, ...) but in
                         // other language it might be allowed which means that has((T) null, ...) from something like
@@ -312,9 +312,17 @@ private Object invokeMethod(final Object delegate, final Class<?> returnType, fi
                         // badly bytecode should either change to use gremlin-language and go away or bytecode should
                         // get a safer way to be translated to a traversal with more explicit calls that don't rely
                         // on reflection.
-                        if (methodName.equals(GraphTraversal.Symbols.has) && newArguments.length > 0 && null == newArguments[0] &&
-                            method.getParameterTypes()[0].isAssignableFrom(org.apache.tinkerpop.gremlin.structure.T.class)) {
-                            found = false;
+                        Class<?>[] parametersTypes = method.getParameterTypes();
+                        if (methodName.equals(GraphTraversal.Symbols.has) && newArguments.length > 0) {
+                            //first case has((T)null, ...) instead of has((String)null, ...)
+                            if (null == newArguments[0] &&
+                                    parametersTypes[0].isAssignableFrom(org.apache.tinkerpop.gremlin.structure.T.class)) {
+                                found = false;
+                            } else if (newArguments[newArguments.length - 1] == null && parametersTypes[newArguments.length - 1] == P.class) {
+                                //the second case has(String, String, (P)(null)) instead of has(String,String, (Object)null)
+                                //or has(String, (P)(null)) instead of has(String, (Object)null)
+                                found = false;
+                            }
                         }
 
                         if (found) {

gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/jsr223/JavaTranslatorTest.java

@@ -0,0 +1,89 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.tinkerpop.gremlin.jsr223;
+
+import org.apache.tinkerpop.gremlin.process.traversal.Bytecode;
+import org.apache.tinkerpop.gremlin.process.traversal.P;
+import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
+import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
+import org.apache.tinkerpop.gremlin.structure.util.empty.EmptyGraph;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class JavaTranslatorTest {
+    private GraphTraversalSource g = EmptyGraph.instance().traversal();
+    private JavaTranslator<GraphTraversalSource, Traversal.Admin<?, ?>> translator = JavaTranslator.of(EmptyGraph.instance().traversal());
+
+    @Test
+    public void shouldTranslateHasWithObjectThirdArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "knows", "weight", 1.0);
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("knows", "weight", 1.0).asAdmin(), translation);
+    }
+
+    @Test
+    public void shouldTranslateHasWithPredicateThirdArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "knows", "weight", P.eq(1.0));
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("knows", "weight", P.eq(1.0)).asAdmin(), translation);
+    }
+
+    @Test
+    public void shouldTranslateHasWithNullThirdArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "knows", "weight", null);
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("knows", "weight", (String) null).asAdmin(), translation);
+    }
+
+    @Test
+    public void shouldTranslateHasWithObjectSecondArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "weight", 1.0);
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("weight", 1.0).asAdmin(), translation);
+    }
+
+    @Test
+    public void shouldTranslateHasWithPredicateSecondArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "weight", P.eq(1.0));
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("weight", P.eq(1.0)).asAdmin(), translation);
+    }
+
+    @Test
+    public void shouldTranslateHasWithNullSecondArgValue() {
+        final Bytecode bytecode = new Bytecode();
+        bytecode.addStep("E");
+        bytecode.addStep("has", "weight", null);
+        final Traversal.Admin<?, ?> translation = translator.translate(bytecode);
+        assertEquals(g.E().has("weight", (String) null).asAdmin(), translation);
+    }
+
+}