The specification says that event methods (bind/unbind/updated) support the following method signatures:
void <method-name>(ServiceReference);
void <method-name>(<parameter-type>);
void <method-name>(<parameter-type>, Map);
This works well for bind and unbind. But for updated only the ServiceReference signature is accepted. The other two signatures cause an error.
See https://bugs.eclipse.org/bugs/show_bug.cgi?id=492645