I apologize for any confusion, the Apache Commons IO library does not contain a class called "JsonFilter" that specifically deals with JSON files, it provides a set of I/O utilities, including file manipulation, file filters, and file comparators.

You can use the FileFilterUtils class to create a filter that accepts or rejects files based on their file name or extension. Here is an example of how to use the FileFilterUtils.suffixFileFilter() method to create a filter that only accepts files with the ".json" extension:

import org.apache.commons.io.filefilter.FileFilterUtils;
import java.io.File;
import java.io.FileFilter;

public class JsonFileFilterExample {
    public static void main(String[] args) {
        File dir = new File("/path/to/directory");
        FileFilter jsonFilter = FileFilterUtils.suffixFileFilter(".json");
        File[] jsonFiles = dir.listFiles(jsonFilter);
        for (File file : jsonFiles) {
            System.out.println(file.getName());
        }
    }
}

This example uses the FileFilterUtils.suffixFileFilter() method to create a filter that only accepts files with the ".json" extension. It then applies the filter to the files in a directory and prints the names of the files that were accepted by the filter.

Note that this filter only checks the file extension and not the content or structure of the file.

You can also use other methods of the FileFilterUtils class to create filters that accept or reject files based on other criteria such as size, modification date, etc.