How is the metaphor of the caged bird in Paul Laurence Dunbar’s poem relevant to sonny's blue

In "Caged Bird," poet Maya Angelou describes a bird with clipped wings. Its feet have been tied, and it has been placed in a cage that prevents it from flying away. Despite its fear, the caged bird continues to sing of freedom. Angelou describes the joy that a free bird takes in soaring through the sky. Angelou then describes a bird that has been caged, its feet tied and wings clipped. The caged bird rails against its imprisonment. In spite of its fear, it sings of freedom.