> ## Documentation Index
> Fetch the complete documentation index at: https://docs.open-metadata.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Create the Java ClassConverter

# Create the Java ClassConverter

**If and only if you had to use the `oneOf` property type on your connector's JSON Schema you also need to implement a Java ClassConverter to be able to instantiate the correct class from the configuration.**

Without this, Java doesn't know the proper Class to instantiate and it wouldn't work as expected.

<Tip>
  This is necessary even if you are indirectly using a `oneOf` property by referencing another JSON Schema that uses it.
</Tip>

## Implementing your ClassConverter

In order to implement the `ClassConverter` you need to create a new file within

[`openmetadata-service/src/main/java/org/openmetadata/service/secrets/converter`](https://github.com/open-metadata/OpenMetadata/tree/main/openmetadata-service/src/main/java/org/openmetadata/service/secrets/converter)

There you should create a new public class that extends `ClassConverter`. The easiest way to achieve this is to use another `ClassConverter` as a reference.

### Example - MysqlConnectionClassConverter.java

Here we will see how to create a ClassConverter for the MysqlConnection, where we define the `authType` using the `oneOf` attribute.

<Tip>
  The file will be shortened and parts of it will be replaced with `...` for readability.
</Tip>

<Steps>
  <Step title="Before anything else you need">
    Before anything else you need to remember to import the needed classes.

    In this example we need to import the `MysqlConnection` itself and both the `IamAuthConfig` and `basicAuth`. It is important to remember that this classes are generated from the JSON Schema and can be found within `openmetadata-spec/target/classes/org/openmetadata/schema/services/connections`.

    If you remember from [Define the JSON Schema](/v1.12.x/developers/contribute/developing-a-new-connector/define-json-schema), the MysqlConnection uses `oneOf` to define the `authType` property:

    ```json theme={null}
        ...
        "authType": {
          "title": "Auth Configuration Type",
          "description": "Choose Auth Config Type.",
          "oneOf": [
            {
              "$ref": "./common/basicAuth.json"
            },
            {
              "$ref": "./common/iamAuthConfig.json"
            }
          ]
        },
        ...
    ```
  </Step>

  <Step title="With the needed imports in">
    With the needed imports in place, now it is time to extend the `ClassConverter` class to create the `MysqlConnectionClassConverter`.

    We are overriding the `convert` method and going the following:

    1. Creating a `MysqlConnection` instance from the json object received
    2. Getting the `AuthType` configuration and trying to use it to instantiate either a `basicAuth` or a `IamAuthConfig`. The first success will be returned.
    3. We set the `AuthType` to be this newly instantaited class
    4. We return the `MysqlConnection` instance.
  </Step>
</Steps>

## Making your ClassConverter visible

Now that your ClassConverter is implemented you need to add it to the [`ClassconverterFactory.java`](https://github.com/open-metadata/OpenMetadata/blob/main/openmetadata-service/src/main/java/org/openmetadata/service/secrets/converter/ClassConverterFactory.java) file, located in the same path.

### Example - MysqlConnectionClassconverter

<Tip>
  The file will be shortened and parts of it will be replaced with `...` for readability.
</Tip>

<Steps>
  <Step title="Before anything else you need">
    Before anything else you need to remember to import your `ClassConverter`
  </Step>

  <Step title="Now you just need to">
    Now you just need to add a new `Map.entry` to the `converterMap`.
  </Step>
</Steps>

## Next Step

Now that the code is ready, let's learn how to test it!

<Card title="Test It" href="/v1.12.x/developers/contribute/developing-a-new-connector/test-it">
  Learn how to test your new connector!
</Card>