Remove duplicate keys in yaml

[traceyyoshima]

In Yaml, a key may contain . like a.b.c:true.
In Spring, the values are resolved like properties so multiple values may be mapped to a single configuration property.

--- 
a: 
  b: 
    c: true
  b.c: ~
a.b: 
  c: false

@sanagaraj-pivotal requested a recipe to remove the duplicate keys
that prioritizes the last matched value.

Example
Choose 8080:

server.port: 9999
server:
  port: 8080

Choose 9999:

server:
  port: 8080
server.port: 9999