In Jakarata EE 9, the JAX-B API moves into the jakarta.xml.bind package space. Currently, BasicAuthHttpConnectionFactory uses javax.xml.bind.DatatypeConverter which is not available in a Jakarta EE 9 environment. If you only support Java 8 and later, switching to java.util.Base64 would allow the same code to work with both Jakarta EE 8 and Jakarta EE 9.