ridljar: javadoc & Override

Javadoc: apply formatting and remove the warning "empty <p> tag".

@Override public String toString()
@Override public boolean equals(Object obj)
@Override public int hashCode()

Change-Id: I64b63d01015535d386ac584831c4ef6e371e863d
Reviewed-on: https://gerrit.libreoffice.org/10453
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>