E.g. use the Javadoc Wizard or something else which accesses an Element, changes its Javadoc comment only, and saves the file. If you start with a method such as:

public /* or private? */ void foo () {
  if (condition)
    throw new Exception ();
}

you will end up with:

/** Foo.
*/
public void foo() {
  if (condition)
  throw new Exception ();
}

Note that whitespace in the method header is normalized, body is reindented, etc. Regardless of whether these things are done correctly or not, changing the Javadoc should simply not affect anything o
utside the Javadoc at all. Otherwise users will not trust the Javadoc Wizard and related tools.