ClassLoader currentClassLoader  = Thread.currentThread().getContextClassLoader();
ClassLoader classLoaderWithEndorsedLibs = new URLClassLoader(new URL[]{URLOfMyAddedJar} , currentClassLoader );
try {
    Thread.currentThread().setContextClassLoader(classLoaderWithEndorsedLibs);
   /*do my work which requires the jar*/
} catch(){...}finally{
   Thread.currentThread().setContextClassLoader(currentClassLoader );
}