Optional
· A value-semantic, type-safe wrapper for representing 'optional' (or 'nullable') objects of a given type. An optional object may or may not contain a value of the underlying type.
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window boost_optional-1.81.0.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
