Registers the supplied transformer. All future class definitions will be seen by the transformer, except definitions of classes upon which any registered transformer is dependent. The transformer is called when classes are loaded, when they are {@linkplain #redefineClasses redefined}. and if
canRetransform is true, when they are {@linkplain #retransformClasses retransformed}. See {@link java.lang.instrument.ClassFileTransformer#transform ClassFileTransformer.transform} for the orderof transform calls. If a transformer throws an exception during execution, the JVM will still call the other registered transformers in order. The same transformer may be added more than once, but it is strongly discouraged -- avoid this by creating a new instance of tranformer class.
This method is intended for use in instrumentation, as described in the {@linkplain Instrumentation class specification}.
@param transformer the transformer to register
@param canRetransform can this transformer's transformations be retransformed
@throws java.lang.NullPointerException if passed a null transformer
@throws java.lang.UnsupportedOperationException if canRetransform is true and the current configuration of the JVM does not allow retransformation ( {@link #isRetransformClassesSupported} is false)
@since 1.6