Minor Description
The org.apache.kafka.common.utils.Base64 class defers Base64 encoding/decoding to the java.util.Base64 class beginning with JRE 1.8 but leverages javax.xml.bind.DatatypeConverter under JRE 1.7. The implementation of the encodeToString(bytes[]) method returned under JRE 1.7 by Base64.urlEncoderNoPadding() blindly removes the last two trailing characters of the Base64 encoding under the assumption that they will always be the string "==" but that is incorrect; padding can be "=", "==", or non-existent.
For example, this statement:
Base64.urlEncoderNoPadding().encodeToString(
"{\"alg\":\"none\"}".getBytes(StandardCharsets.UTF_8));
Yields this, which is incorrect: (because the padding on the Base64 encoded value is "=" instead of the assumed "==", so an extra character is incorrectly trimmed):
eyJhbGciOiJub25lIn
The correct value is:
eyJhbGciOiJub25lIn0
There is also no Base64.urlDecoder() method, which aside from providing useful functionality would also make it easy to write a unit test (there currently is none).
