Javadoc linking to a class in another package
For another package use this syntax:
{@link package.class#member label}
In your case this should be:
{@link com.myproject.Shapes.Square Square}
If you want to show only the class name then use the label, if complete path is desired then label is not required.
Reference: http://docs.oracle.com/javase/7/docs/technotes/tools/windows/javadoc.html#link
The correct syntax variants are
{@link [<package>.]<class>[#<method>]}
{@link #<method>}
You were missing a complete package. The following example should be correct
{@link com.myproject.Shapes.Square}
^^^^^^