jsonschema2pojo
Generate Java types from JSON or JSON Schema for data-binding
...If additionalProperties is specified and set to the boolean value false, then the generated Java type does not support additional properties. If the additionalProperties node is undefined (not present), null or empty, then a new bean property named "additionalProperties", of type Map<String,Object> is added to the generated type (with appropriate accessors). The accessors are annotated to allow Jackson to marshal/unmarshal unrecognised (additional) properties found in JSON data from/to this map.