Fix return type of child classes

Author: mjdecker

_notes/software-architecture/refactoring/catalog.md

@@ -35,7 +35,7 @@ layout: notes
 
 
 # Replace Conditional with Polymorphism (after)
-<img src="https://yuml.me/diagram/class/[｛abstract｝bird|%20|%20+%20get_speed():number｛abstract｝],[european|%20|%20+%20get_speed():real],[african|%20|%20+%20get_speed():real],[norwegian_blue|%20|%20+%20get_speed():real],[｛abstract｝bird]^-[european],[｛abstract｝bird]^-[african],[｛abstract｝bird]^-[norwegian_blue]" alt="Replace Conditional with Polymorphism example"/>
+<img src="https://yuml.me/diagram/class/[｛abstract｝bird|%20|%20+%20get_speed():number｛abstract｝],[european|%20|%20+%20get_speed():number],[african|%20|%20+%20get_speed():number],[norwegian_blue|%20|%20+%20get_speed():number],[｛abstract｝bird]^-[european],[｛abstract｝bird]^-[african],[｛abstract｝bird]^-[norwegian_blue]" alt="Replace Conditional with Polymorphism example"/>
 
 # Change Bidirectional Association to Unidirectional - Before
 ![](https://yuml.me/diagram/class/[order]<*-1%3e[customer])