Filter out sythetic fields from FieldQueryMapEncoder

core/src/main/java/feign/querymap/FieldQueryMapEncoder.java

@@ -17,6 +17,7 @@
 import feign.codec.EncodeException;
 import java.lang.reflect.Field;
 import java.util.*;
+import java.util.stream.Collectors;
 
 /**
  * the query map will be generated using member variable names as query parameter names.
@@ -66,14 +67,11 @@ private ObjectParamMetadata(List<Field> objectFields) {
     }
 
     private static ObjectParamMetadata parseObjectType(Class<?> type) {
-      List<Field> fields = new ArrayList<Field>();
-      for (Field field : type.getDeclaredFields()) {
-        if (!field.isAccessible()) {
-          field.setAccessible(true);
-        }
-        fields.add(field);
-      }
-      return new ObjectParamMetadata(fields);
+      return new ObjectParamMetadata(
+          Arrays.stream(type.getDeclaredFields())
+              .filter(field -> !field.isSynthetic())
+              .peek(field -> field.setAccessible(true))
+              .collect(Collectors.toList()));
     }
   }
 }

core/src/test/java/feign/querymap/PropertyQueryMapEncoderTest.java → core/src/test/java/feign/querymap/BeanQueryMapEncoderTest.java

@@ -22,7 +22,10 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
-public class PropertyQueryMapEncoderTest {
+/**
+ * Test for {@link BeanQueryMapEncoder}
+ */
+public class BeanQueryMapEncoderTest {
 
   @Rule
   public final ExpectedException thrown = ExpectedException.none();

core/src/test/java/feign/querymap/FieldQueryMapEncoderTest.java

@@ -0,0 +1,67 @@
+/**
+ * Copyright 2012-2018 The Feign Authors
+ *
+ * Licensed 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 feign.querymap;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import java.util.HashMap;
+import java.util.Map;
+import feign.QueryMapEncoder;
+
+/**
+ * Test for {@link FieldQueryMapEncoder}
+ */
+public class FieldQueryMapEncoderTest {
+
+  @Rule
+  public final ExpectedException thrown = ExpectedException.none();
+
+  private final QueryMapEncoder encoder = new FieldQueryMapEncoder();
+
+  @Test
+  public void testDefaultEncoder_normalClassWithValues() {
+    final Map<String, Object> expected = new HashMap<>();
+    expected.put("foo", "fooz");
+    expected.put("bar", "barz");
+    final NormalObject normalObject = new NormalObject("fooz", "barz");
+
+    final Map<String, Object> encodedMap = encoder.encode(normalObject);
+
+    assertEquals("Unexpected encoded query map", expected, encodedMap);
+  }
+
+  @Test
+  public void testDefaultEncoder_normalClassWithOutValues() {
+    final NormalObject normalObject = new NormalObject(null, null);
+
+    final Map<String, Object> encodedMap = encoder.encode(normalObject);
+
+    assertTrue("Non-empty map generated from null getter: " + encodedMap, encodedMap.isEmpty());
+  }
+
+  class NormalObject {
+
+    private NormalObject(String foo, String bar) {
+      this.foo = foo;
+      this.bar = bar;
+    }
+
+    private final String foo;
+    private final String bar;
+  }
+
+}