Gradle: Passing arguments to compiler and javadoc. (Getting rid of "warning: sun.misc.Unsafe is internal proprietary API and may be removed in a future release")

build.gradle

apply plugin: 'java'

compileJava {
    // This only works when forking and passing 'javac' as an executable
    options.compilerArgs << '-XDignore.symbol.file'    
    options.fork = true
    options.forkOptions.executable = 'javac'
}


javadoc {
    // These get ignored
    // options.addStringOption('XDignore.symbol.file', null)
    // options.addStringOption('XDignore.symbol.file')
    
    // This one fails build - I am assuming it's trying to parse ''
    // options.addStringOption('XDignore.symbol.file')

    // This works, but it's an ugly hack
    options.addStringOption('XDignore.symbol.file', '-quiet')
}

build.xml

<?xml version="1.0" encoding="UTF-8"?>

<project name="gradleTest" basedir=".">
    <property name="dir.main.src" value="src/main/java"/>
    <property name="dir.main.build" value="build/classes/main"/>
    <property name="dir.docs" value="build/docs/javadoc"/>

    <target name="clean">
        <delete dir="build"/>
    </target>

    <target name="compileJava">
        <mkdir dir="${dir.main.build}"/>
        <javac destdir="${dir.main.build}"
               includeAntRuntime="false"
               nowarn="true">
            <compilerarg value="-XDignore.symbol.file"/>
            <src path="${dir.main.src}"/>
        </javac>
    </target>

    <target name="javadoc">
        <javadoc sourcepath="${dir.main.src}"
                 destdir="${dir.docs}">
            <arg value="-XDignore.symbol.file"/>
        </javadoc>
    </target>
</project>

Sample.java

//Should be placed in './src/main/java/org/bore/sample' directory
package org.bore.sample;

import sun.misc.Unsafe;

public class Sample {

    public int foo() {
        return Unsafe.getUnsafe().pageSize();
    }
}