I have a wordpress endpoint and have some json data. Unfortunately I don't know how to return this json data in the function. I tried json_decode but it returned nothing. Then the endpoint will work. If I use json_encode it returns the data but also includes newlines and other stuff. The problem seems to be with the syntax, since it's already a complete json that I have. How to return something already in json syntax?

add_action('wp_ajax_nopriv_inboundCall', 'testFunction');
add_action('wp_ajax_inboundCall', 'testFunction');
 
function testFunction() {
    
    echo json_decode('{
        "testData": [
          {
            "_id": "1",
            "name": "testName1"
          },
          {
            "_id": "2",
            "name": "testName2"
          },
        ],
        "testState": {
          "1": [
            1,
            0
          "2": [
            1,
            0
          ]
         }
       }'); 

      die(); 
}