Problems with Freemarker - utils.digest.hmac Hmac SHA256 and base 64 encoding?

This answer is misleading. 

The problem is that base64.encode and digest.hmac take only strings as input.

Most Base64 suites take a binary array.   Like Spring:

https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/util/Base64Utils.html#encode-byte:A-

Why Base64 encode a binary array that will not encode to a string?  It increases the entropy of the result.