You can show associations as attributes in classifiers in diagrams.
You must be in the C/C++ perspective and have a diagram open in the
diagram editor.
To show an association as an attribute, in the diagram editor, right-click
an association; then click .
The association is removed from the diagram and is added to the source
classifier as an attribute.
Tip: You can also drag an association onto the attribute
compartment of the source of the association to show the association as an
attribute.