Javadoc tells you the return type of boolean, so saying true|false is redundant. It's best to say the conditions when it returns true or false - True if conversation contains unread messages; false otherwise. It's super minor though, javadoc can be annoying

https://www.liferay.com/community/wiki/-/wiki/Main/Javadoc+Guidelines#section-Javadoc+Guidelines-@return+tag