anchor.diff:  a property with the key does not exists, eg `file.url:/some/path` where
   the default value is the text after the colon (eg /some/path).
   
  -[NOTE]
  -====
  -Do not use colon in the property key. The colon is used as a separator
  +NOTE: Do not use colon in the property key. The colon is used as a separator
   token when you are providing a default value.
  -====
   
   == Defining location
   
  
positive.code: </camelContext>
  ----
  
  [NOTE]
  ====
  The location attribute (on propertyPlaceholder tag) is not mandatory
  ====
  
  Here we have a Camel XML route where we have defined the
  `<propertyPlaceholder>` to use a custom function, which we refer to be the
  
negative.code: 
  Where `APP_HOME` is an OS environment.
  
  NOTE: Some OS'es (such as Linux) do not support dashes in environment variable names,
  so here we are using `APP_HOME`. But if you specify `APP-HOME` then Camel 3 will automatic lookup
  the value as `APP_HOME` (with underscore) as fallback.
  
  You can have multiple placeholders in the same location, such as:
  
  