Android Studio Cloud Endpoint project Maven enhance goal fails with command line too long - maven

Question

Using Android Studio, I have created an Android project with a cloud endpoint backend (Tools > Google Cloud Endpoints > Generate AppEngine Backend). The initial setup works and I am able to have the Android app see the exposed cloud endpoints.
However after adding more components to the AppEngine project (more entities, endpoints, servlets, etc) the AppEngine build fails during the Maven goal appengine-maven-plugin:enhance with a command line too long error.
Upon researching this, it appears this goal delegates to the datanucleus-maven-plugin:enhance goal (please see the Maven mojo source code here). When I run the goal from the command line using Maven's -X option, I see that the enhancer attempts to run on all classes (servlets, non-entities, etc) and that the command line length exceeds Window's limit.
The solution to this appears to be specifying only the specific entities to be enhanced. This post describes how the Maven plugin can be configured for that.
This all seems fair enough, but my attempts to configure the plugin from my pom.xml have no effect. Executing from the command line, I see the message that the datanucleus enhance goal is configured with it's default configuration and not from the pom.
I am a Maven newbie, so it'd be very much appreciated if someone could explain what the Maven appengine enhance mojo is expecting for a configuration which the source code seems to be grabbing in the line 115: mojoDescriptor.getMojoConfiguration()
My pom.xml looks like this:
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<packaging>war</packaging>
<version>1.0</version>
<groupId>com.myproject</groupId>
<artifactId>MyProject</artifactId>
<properties>
<appengine.target.version>1.8.3</appengine.target.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!--Found by examining mvn com.google.appengine:appengine-maven-plugin:1.8.3:enhance -X
see https://code.google.com/p/appengine-maven-plugin/source/browse/src/main/java/com/google/appengine/AppengineEnhancerMojo.java?spec=svn834b839bf5deab60499ecfb85facd55f06f8e258&r=834b839bf5deab60499ecfb85facd55f06f8e258
-->
<appengine.enhancerApi>JPA</appengine.enhancerApi>
</properties>
<dependencies>
<!-- Compile/runtime dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-endpoints</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.geronimo.specs</groupId>
<artifactId>geronimo-jpa_2.0_spec</artifactId>
<version>1.1</version>
</dependency>
<dependency>
<groupId>net.sf.jsr107cache</groupId>
<artifactId>jsr107cache</artifactId>
<version>1.1</version>
</dependency>
<dependency>
<groupId>com.google.appengine.orm</groupId>
<artifactId>datanucleus-appengine</artifactId>
<version>2.1.2</version>
</dependency>
<dependency>
<groupId>com.googlecode.json-simple</groupId>
<artifactId>json-simple</artifactId>
<version>1.1.1</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.ganyo</groupId>
<artifactId>gcm-server</artifactId>
<version>1.0.2</version>
</dependency>
<!-- Test Dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-maven-plugin</artifactId>
<version>3.2.0-release</version>
</dependency>
</dependencies>
<build>
<!-- for hot reload of the web application-->
<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes
</outputDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<version>2.5.1</version>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<webXml>
${project.build.directory}/generated-sources/appengine-endpoints/WEB-INF/web.xml
</webXml>
<webResources>
<resource>
<!-- this is relative to the pom.xml directory -->
<directory>
${project.build.directory}/generated-sources/appengine-endpoints
</directory>
<!-- the list has a default value of ** -->
<includes>
<include>WEB-INF/*.discovery</include>
<include>WEB-INF/*.api</include>
</includes>
</resource>
</webResources>
</configuration>
</plugin>
<!--
No config settings get applied?
-->
<plugin>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-maven-plugin</artifactId>
<version>3.2.0-release</version>
<configuration>
<fork>false</fork>
<verbose>true</verbose>
<metadataIncludes>some_path</metadataIncludes>
</configuration>
<executions>
<execution>
<id>default-enhance</id>
<configuration>
<fork>false</fork>
<verbose>true</verbose>
<metadataIncludes>some_path</metadataIncludes>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>1.8.3</version>
<configuration>
<enableJarClasses>false</enableJarClasses>
</configuration>
<executions>
<execution>
<goals>
<goal>endpoints_get_discovery_doc</goal>
<!--goal>endpoints_get_client_lib</goal-->
<goal>enhance</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-maven-plugin</artifactId>
<version>3.2.0-release</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
Thanks!