The program violates the Enterprise JavaBeans specification by using AWT/Swing.
The Enterprise JavaBeans specification requires that every bean provider follow a set of programming guidelines designed to ensure that the bean will be portable and behave consistently in any EJB container [1].
In this case, the program violates the following EJB guideline:
"An enterprise bean must not use the AWT functionality to attempt to output information to a display, or to input information from a keyboard."
A requirement that the specification justifies in the following way:
"Most servers do not allow direct interaction between an application program and a keyboard/display attached to the server system."
[1] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 575
[2] The Enterprise JavaBeans 2.1 Specification Sun Microsystems