>clearBody</code> is called, the message can now be
 both read from and written to.

 <p>
 <code>MapMessage</code> objects support the following conversion table. The marked cases must be supported. The unmarked
 cases must throw a <code>JMSException</code>. The <code>String</code>-to-primitive conversions may throw a runtime exception if
 the primitive's <code>valueOf()</code> method does not accept it as a valid <code>String</code> representation of the
 primitive.

 <p>
 A value written as the row type c