Let's consider XMLEventFactory.newFactory(String factoryId, ClassLoader classLoader) spec excerpt:

   * If {@code factoryId} is "javax.xml.stream.XMLEventFactory",
   * use the service-provider loading facilities, defined by the
   * {@link java.util.ServiceLoader} class, to attempt to locate and load an
   * implementation of the service using the specified {@code ClassLoader}.
   * If {@code classLoader} is null, the {@linkplain
   * java.util.ServiceLoader#load(java.lang.Class) default loading mechanism} will apply:

Above excerpt refers to java.util.ServiceLoader#load(java.lang.Class) method for null classLoader case.

Similarly java.util.ServiceLoader#load(java.lang.Class, ClassLoader) should be referred for the case of non null classLoader; for instance like it's presented below:

   * If {@code factoryId} is "javax.xml.stream.XMLEventFactory",
   * use the service-provider loading facilities, defined by the
   * {@link java.util.ServiceLoader} class, to attempt to {@linkplain java.util.ServiceLoader#load(java.lang.Class, java.lang.ClassLoader) locate and load} an
   * implementation of the service using the specified {@code ClassLoader}.

The similar change should be applied:
to XMLInputFactory.newFactory(String factoryId, ClassLoader classLoader)
and to XMLOutputFactory.newFactory(String factoryId, ClassLoader classLoader).