anchor.diff:  implementation for every method, which allows application developers to only override
   the methods they care about.  To use it, simply create an implementation of
   this interface and register it using the `mp.openapi.filter` configuration
  -key, where the value is the qualified name of the filter.
  +key, where the value is the fully qualified name of the filter class.
   
   .Sample META-INF/microprofile-config.properties
   [code,property]
  
positive.code: 
  The https://github.com/eclipse/microprofile-open-api/blob/master/api/src/main/java/org/eclipse/microprofile/openapi/OASFactory.java[OASFactory] is used to create all of the elements of an OpenAPI tree.
  
  For example, the following snippet creates a simple https://github.com/eclipse/microprofile-open-api/blob/master/api/src/main/java/org/eclipse/microprofile/openapi/models/info/Info.java[Info] element that contains a title, description and version.
  
  [source,java]
  ----
  
negative.code: === Static OpenAPI files
  
  Application developers may wish to include a pre-generated OpenAPI document that
  was written separately from the code (e.g. with an editor such as https://editor.swagger.io/[this]).
  
  Depending on the scenario, the document may be fully complete or partially complete.
  If a document is fully complete then the application developer will want to set the
  `mp.openapi.scan.disable` configuration property to `true`.  If a document is partially
  complete, then the application developer will need to augment the OpenAPI snippet
  with annotations, programming model, or via the filter.
  
  ==== Location and formats
  
  Vendors are required to fetch a single document with extension of `yml`, `yaml` or
  `json`, inside the application's `META-INF/openapi` folder.  If there is more than
  one document found that matches one of these extensions the behavior of which file
  is chosen is undefined (i.e. each vendor may implement their own logic), which means
  that application developers should only place a single document into that folder.
  
  === Programming model
  