Android : NoClassDefFoundError when running Android app built with Maven

I'm getting a NoClassDefFoundError for a class that exists in my Android App. I'm building with maven and the class that can't be found is LruBitmapCache.java, an implementation of the Volley ImageCache which I have written inside my android project:

public class LruBitmapCache extends LruCache<String, Bitmap> implements ImageCache
{
    public static int getDefaultLruCacheSize()
    {
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
        final int cacheSize = maxMemory / 8;

        return cacheSize;
    }

    public LruBitmapCache()
    {
        this(getDefaultLruCacheSize());
    }

    public LruBitmapCache(int sizeInKiloBytes)
    {
        super(sizeInKiloBytes);
    }

    @Override
    protected int sizeOf(String key, Bitmap value)
    {
        return value.getRowBytes() * value.getHeight() / 1024;
    }

    @Override
    public Bitmap getBitmap(String url)
    {
        return get(url);
    }

    @Override
    public void putBitmap(String url, Bitmap bitmap)
    {
        put(url, bitmap);
    }
}

My pom.xml is as follows

<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">
    <parent>
        <groupId>com.x.y</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../../parent</relativePath>
    </parent>

    <modelVersion>4.0.0</modelVersion>
    <artifactId>android-project</artifactId>
    <packaging>apk</packaging>

    <build>
        <plugins>
            <plugin>
                <groupId>com.jayway.maven.plugins.android.generation2</groupId>
                <artifactId>android-maven-plugin</artifactId>
                <version>3.8.2</version>
                <configuration>
                    <sdk>
                        <platform>19</platform>
                    </sdk>
                    <deleteConflictingFiles>true</deleteConflictingFiles>
                    <undeployBeforeDeploy>false</undeployBeforeDeploy>
                    <device>usb</device>
                </configuration>
                <extensions>true</extensions>
            </plugin>

            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>android</groupId>
            <artifactId>android</artifactId>
            <version>4.4.2_r3</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.google.android</groupId>
            <artifactId>support-v4</artifactId>
            <version>r7</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.1</version>
        </dependency>

        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.12</version>
        </dependency>

        <dependency>
            <groupId>com.googlecode.androidannotations</groupId>
            <artifactId>androidannotations</artifactId>
            <version>2.7.1</version>
        </dependency>

        <dependency>
            <groupId>com.mcxiaoke.volley</groupId>
            <artifactId>library</artifactId>
            <version>1.0.6</version>
        </dependency>

        <dependency>
            <groupId>fr.avianey</groupId>
            <artifactId>facebook-android-api</artifactId>
            <version>3.17.1</version>
        </dependency>

        <dependency>
            <groupId>org.twitter4j</groupId>
            <artifactId>twitter4j-core</artifactId>
            <version>4.0.2</version>
        </dependency>

    </dependencies>
</project>

I'm building and deploying the app with "mvn install android:deploy", which successfully deploys the app to the device, but when I try and open the application I get the NoClassDefFoundError (since some application code attempts to initialize the LruBitmapCache). I had assumed it might have been because the Volley dependency wasn't being included in the classes, but I'm not 100% sure how the dex classes work. Does anyone have any idea why this could be happening or has anyone had this before? Faulty classes? Dependency conflict? Any help is appreciated.