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# Fixing a PHP client library include and exclude fields bug

The Marketing API’s [PHP client library](https://github.com/mailchimp/mailchimp-marketing-php) was not handling the `fields` and `exclude_fields` query parameters correctly. We’ve fixed a bug in the client generation that will process the arrays as CSV strings. This change will affect version 3.0.35 of the PHP client library.

A user reported unexpected behavior when passing in an array of strings, and we discovered that the Swagger Codegen utility was not parsing the `collectionFormat` for query parameters as expected.