What causes LinkageError: loader constraint violation:... javax/activation/DataHandler in JBoss EAP?

Issue

• When attempting to set the DataHandler for a text/html mail message we see the following error in our log:

  ERROR [STDERR.write:156] java.lang.LinkageError: loader constraint violation: loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) previously initiated loading for a different type with name "javax/activation/DataHandler"
  ERROR [STDERR.write:156]      at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:945)
  ERROR [STDERR.write:156]      at javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:1617)
  ERROR [STDERR.write:156]      at javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:1598)