Chicken Cheddar Rice with Asparagus

nonstick cooking spray 2 cups water 8 ounces boneless, skinless, chicken thigh meat, trimmed of fat and cut into bite-size pieces 1 ½ cups diced onion 1 cup uncooked brown rice, preferably parboiled variety 4 medium garlic cloves, minced 2 teaspoons sodium-free chicken bouillon granules ½ teaspoon dried thyme leaves 2 cups fresh asparagus tips, broken in 2-inch pieces, or frozen French cut green beans, thawed ½ teaspoon salt 2 ounces (½ cup) reduced-fat sharp Cheddar cheese, shredded