Revert "chore: convert OAuth2TokenProvider to Kotlin"

package com.fsck.k9.mail.oauth

package com.fsck.k9.mail.oauth;

import com.fsck.k9.mail.AuthenticationFailedException

interface OAuth2TokenProvider {

    companion object {

import com.fsck.k9.mail.AuthenticationFailedException;

public interface OAuth2TokenProvider {

    /**

     * A default timeout value to use when fetching tokens.

     */

        const val OAUTH2_TIMEOUT = 30000L

    }

    int OAUTH2_TIMEOUT = 30000;

    /**

     * Fetch the primary email found in the id_token additional claims,

     * if it is available.

     *

     * > Some providers, like Microsoft, require this as they need the primary account email to be the username,

     * not the email the user entered

     *

     * @return the primary email present in the id_token, otherwise null.

     */

    val primaryEmail: String?

        @Throws(AuthenticationFailedException::class)

        get

    /**

     * Fetch a token. No guarantees are provided for validity.

     */

    @Throws(AuthenticationFailedException::class)

    fun getToken(timeoutMillis: Long): String

    String getToken(long timeoutMillis) throws AuthenticationFailedException;

    /**

     * Invalidate the token for this username.

     *

     * <p>

     * Note that the token should always be invalidated on credential failure. However invalidating a token every

     * single time is not recommended.

     *

     * <p>

     * Invalidating a token and then failure with a new token should be treated as a permanent failure.

     */

    fun invalidateToken()

    void invalidateToken();

}