There is no way to do this for public methods. The standard practice (even in quite a few JDK classes) is to indicate that the method or constructor is not meant for public use.
There is a plan to add an @exclude tag in the future:
@exclude – for API to be excluded from
generation by Javadoc. Programmer
would mark a class, interface,
constructor, method or field with
@exclude. Presence of tag would cause
API to be excluded from the generated
documentation. Text following tag
could explain reason for exclusion,
but would be ignored by Javadoc.
(Formerly proposed as @hide, but the
term “hide” is more appropriate for
run-time dynamic show/hide
capability.) For more discussion, see:
Feature Request #4058216 in Developer
Connection.