Apache Commons IO library does not have any class that provide json serialization/deserialization functionality, the libraries that you can use for this purpose are Jackson, Gson, and other libraries that provide JSON serialization/deserialization functionality.

The JsonAnyGetter annotation is provided by the Jackson library, which is used to indicate that a method should be used to serialize a property that is not explicitly defined in the class. Here's an example of how you can use the JsonAnyGetter annotation to serialize a Map property in a Java class:

class Person {
    private String name;
    private int age;
    private Map<String, Object> additionalProperties = new HashMap<>();

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @JsonAnyGetter
    public Map<String, Object> getAdditionalProperties() {
        return additionalProperties;
    }

    @JsonAnySetter
    public void setAdditionalProperties(String key, Object value) {
        additionalProperties.put(key, value);
    }
}

In this example, the getAdditionalProperties method is annotated with @JsonAnyGetter, which tells the Jackson library to use this method to serialize any properties that are not explicitly defined in the Person class. The setAdditionalProperties method is annotated with @JsonAnySetter that tells the Jackson library to use this method to deserialize any properties that are not explicitly defined in the Person class.

Keep in mind that you need to have the Jackson library in your classpath in order to use this example.