Specification for Component -- null param behavior not specified

Need to specify behavior if listeners are added/removed with null references
passed as input parameters. By convention, a null input parameter should
result in a NullPointer exception unless otherwise documented. listener
add/remove methods for component have no effect (no exception) if a null
reference is passed as input.

Similarly, passing a listener to remove() that was never added has no
effect and should be documented so the jck can test this case.