when 'factoryId' is null newInstance throws NPE

In StAX javadocs
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I think javadoc should be updated to include this case also -
 i.e, NullPointerException - when factoryId is null

or should this be throwing 'FactoryConfigurationError' ? as this is the same case as
"instance of factory cannot be loaded"

This applies for all the 3 StAX factory classes !

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newInstance

public static XMLEventFactory newInstance(java.lang.String factoryId,
                                          java.lang.ClassLoader classLoader)
                                   throws FactoryConfigurationError

    Create a new instance of the factory

    Parameters:
        factoryId - Name of the factory to find, same as a property name
        classLoader - classLoader to use
    Returns:
        the factory implementation
    Throws:
        FactoryConfigurationError - if an instance of this factory cannot be loaded
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