Implement in plain Java with no dependencies.

config/build.sbt

@@ -20,8 +20,6 @@ fork in run in Test := true
 autoScalaLibrary := false
 crossPaths := false
 
-libraryDependencies += "org.apache.commons" % "commons-lang3" % "3.3.2"
-libraryDependencies += "javax.annotation" % "javax.annotation-api" % "1.2"
 libraryDependencies += "net.liftweb" %% "lift-json" % "2.5" % "test"
 libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % "test"
 

config/src/main/java/com/typesafe/config/impl/ConfigBeanImpl.java

@@ -1,7 +1,5 @@
 package com.typesafe.config.impl;
 
-import org.apache.commons.lang3.reflect.FieldUtils;
-
 import java.beans.BeanInfo;
 import java.beans.IntrospectionException;
 import java.beans.Introspector;
@@ -134,11 +132,6 @@ public class ConfigBeanImpl {
         }
     }
 
-    private static boolean isOptionalProperty(Class clazz, PropertyDescriptor beanProp) {
-        Field field = FieldUtils.getField(clazz, beanProp.getName(), true);
-        return (field.getAnnotationsByType(Optional.class).length > 0);
-    }
-
     // we could magically make this work in many cases by doing
     // getAnyRef() (or getValue().unwrapped()), but anytime we
     // rely on that, we aren't doing the type conversions Config
@@ -273,4 +266,27 @@ public class ConfigBeanImpl {
 
         return false;
     }
+
+    private static boolean isOptionalProperty(Class beanClass, PropertyDescriptor beanProp) {
+        Field field = getField(beanClass, beanProp.getName());
+        if (field == null) {
+            throw new ConfigException.BadBean("Bean property '" + beanProp + "' of class " + beanClass.getName() + " does not exist");
+        }
+        return (field.getAnnotationsByType(Optional.class).length > 0);
+    }
+
+    private static Field getField(Class beanClass, String fieldName) {
+        try {
+            Field field = beanClass.getDeclaredField(fieldName);
+            field.setAccessible(true);
+            return field;
+        } catch (NoSuchFieldException e) {
+            // Don't give up yet. Try to look for field in super class, if any.
+        }
+        beanClass = beanClass.getSuperclass();
+        if (beanClass == null) {
+            return null;
+        }
+        return getField(beanClass, fieldName);
+    }
 }

config/src/test/java/beanconfig/ObjectsConfig.java

@@ -6,23 +6,23 @@ import com.typesafe.config.Optional;
 public class ObjectsConfig {
     public static class ValueObject {
         @Optional
-        private String nullableValue;
-        private String nonNullableValue;
+        private String optionalValue;
+        private String mandatoryValue;
 
-        public String getNonNullableValue() {
-          return nonNullableValue;
+        public String getMandatoryValue() {
+          return mandatoryValue;
         }
 
-        public void setNonNullableValue(String nonNullableValue) {
-          this.nonNullableValue = nonNullableValue;
+        public void setMandatoryValue(String mandatoryValue) {
+          this.mandatoryValue = mandatoryValue;
         }
 
-        public String getNullableValue() {
-          return nullableValue;
+        public String getOptionalValue() {
+          return optionalValue;
         }
 
-        public void setNullableValue(String nullableValue) {
-          this.nullableValue = nullableValue;
+        public void setOptionalValue(String optionalValue) {
+          this.optionalValue = optionalValue;
         }
     }
 

config/src/test/resources/beanconfig/beanconfig01.conf

@@ -95,7 +95,7 @@
     },
     "objects" : {
       "valueObject": {
-        "nonNullableValue": "nonNullValue"
+        "mandatoryValue": "notNull"
       }
     }
 }

config/src/test/scala/com/typesafe/config/impl/ConfigBeanFactoryTest.scala

@@ -167,8 +167,8 @@ class ConfigBeanFactoryTest extends TestUtils {
         val beanConfig: ObjectsConfig = ConfigBeanFactory.create(loadConfig().getConfig("objects"), classOf[ObjectsConfig])
         assertNotNull(beanConfig)
         assertNotNull(beanConfig.getValueObject)
-        assertNull(beanConfig.getValueObject.getNullableValue)
-        assertEquals("nonNullValue", beanConfig.getValueObject.getNonNullableValue)
+        assertNull(beanConfig.getValueObject.getOptionalValue)
+        assertEquals("notNull", beanConfig.getValueObject.getMandatoryValue)
     }
 
     @Test