anchor.diff:  These default values can then be overridden at runtime with a different file located in one of the custom locations.
   
   NOTE: If you use environment variables rather than system properties, most operating systems disallow period-separated key names, but you can use underscores instead (for example, `SPRING_CONFIG_NAME` instead of `spring.config.name`).
  +See <<boot-features-external-config-relaxed-binding-from-environment-variables>> for details.
   
   NOTE: If your application runs in a container, then JNDI properties (in `java:comp/env`) or servlet context initialization parameters can be used instead of, or as well as, environment variables or system properties.
   
  
positive.code: The properties above will bind to a `Map` with `/key1`, `/key2` and `key3` as the keys in the map.
  
  NOTE: For YAML files, the brackets need to be surrounded by quotes for the keys to be parsed properly.
  
  
  [[boot-features-external-config-complex-type-merge]]
  
negative.code: 
  TIP: We recommend that, when possible, properties are stored in lower-case kebab format, such as `my.property-name=acme`.
  
  
  
  [[boot-features-external-config-relaxed-binding-maps]]
  ===== Binding Maps
  When binding to `Map` properties, if the `key` contains anything other than lowercase alpha-numeric characters or `-`, you need to use the bracket notation so that the original value is preserved.
  If the key is not surrounded by `[]`, any characters that are not alpha-numeric or `-` are removed.
  For example, consider binding the following properties to a `Map`:
  