Why does the Ansible URI module convert a string to a boolean?

Issue

• Why does the Ansible URI module convert a string to a boolean?

TASK [Calling testing build] ***************************************************
{
    "content_length": "102",
    "status": 400,
    "changed": false,
    "connection": "close",
    "vary": "Accept, Accept-Language, Origin, Cookie",
    "elapsed": 0,
    "x_api_time": "0.193s",
    "content_language": "en",
    "content_type": "application/json",
    "date": "Tue, 30 Jun 2020 15:31:23 GMT",
    "x_api_product_version": "3.7.1",
    "msg": "Status code was 400 and not [200, 201]: HTTP Error 400: Bad Request",
    "_ansible_no_log": false,
    "x_api_node": "localhost",
    "url": "https://rh-tower.example.org/api/v2/workflow_job_templates/12/launch/",
    "x_api_product_name": "Red Hat Ansible Tower",
    "json": {
        "variables_needed_to_start": [
            "Value True for 'backup_tag' expected to be one of ['True', 'False']."
        ]
    },
    "server": "nginx",
    "content": "{\"variables_needed_to_start\":[\"Value True for 'backup_tag' expected to be one of ['True', 'False'].\"]}",
    "x_api_total_time": "0.240s",
    "allow": "GET, POST, HEAD, OPTIONS",
    "invocation": {
        "module_args": {
            "directory_mode": null,
            "force": false,
            "remote_src": null,
            "status_code": [
                "200",
                " 201"
            ],
            "follow": false,
            "owner": null,
            "body_format": "json",
            "client_key": null,
            "group": null,
            "use_proxy": true,
            "unix_socket": null,
            "unsafe_writes": null,
            "serole": null,
            "content": null,
            "setype": null,
            "follow_redirects": "safe",
            "return_content": true,
            "method": "POST",
            "body": {
                "extra_vars": {
                    "backup_tag": true,
                    "it_mod_tag": "testing"
                }
            },
            "timeout": 30,
            "src": null,
            "dest": null,
            "selevel": null,
            "force_basic_auth": true,
            "removes": null,
            "http_agent": "ansible-httpget",
            "user": "admin",
            "regexp": null,
            "password": "VALUE_SPECIFIED_IN_NO_LOG_PARAMETER",
            "url_password": "VALUE_SPECIFIED_IN_NO_LOG_PARAMETER",
            "url": "https://rh-tower.example.org/api/v2/workflow_job_templates/12/launch/",
            "backup": null,
            "seuser": null,
            "client_cert": null,
            "creates": null,
            "headers": {
                "Content-Type": "application/json"
            },
            "delimiter": null,
            "mode": null,
            "url_username": "admin",
            "attributes": null,
            "validate_certs": false
        }
    },
    "redirected": false
}