i read 'Design Patterns' why Composition inherit Graphy in example Lexi

recently I'm reading Design Patterns: Elements of Reusable Object-Oriented Software

in example Lexi, design of Encapsulating the Formatting Algorithm as follows

here is image

my question is , why Composition inherit Graphy. I think Composition just contains list of Graphy is ok.

This is my first ask question use English...(Hope you can understand me...)