doclint reports missing javadoc for JavaFX property methods that have a property description

For JavaFX properties -- which are defined as attributes that have a xxxxProperty method that returns a subclass of javafx.beans.Observable, a getXxxx method, and an optional setXxxx method -- the description on the property itself is copied to the three public methods by the standard doclet.

When running javadoc with `-Xdoclint:missing" the methods without a javadoc comment body are flagged as missing a comment even when the property itseld does have a comment that will be copied.

This produces a few thousand warnings when build the JavaFX docs with JDK 15.

To reproduce it, either clone the jfx repo and run "gradle javadoc" or else download the JavaFX 15 SDK and run the attached test program as follows:

javadoc -d build --source-path src \
        --module-path /SOMEWHERE/javafx-sdk-15/lib \
        --add-modules javafx.base \
        -Xdoclint:all \
        pkg