checkstyle: don't introduce compile time dep for javadoc.

From checkstyle:
"it is considered bad practice to introduce a compile time dependency for
documentation purposes only. As an example, the import java.util.Date would be
considered referenced with the Javadoc comment {@link Date}. The alternative to
avoid introducing a compile time dependency would be to write the Javadoc
comment as {@link java.util.Date}."
reformatted javadoc comment to 80 chars