How to set DMQ Eligible flag in Spring Boot

You should not have to use SolAdmin. Similar to what link was posted earlier, there is another link with available properties.
Message Properties
You can set all these properties via the JMS Template. The following is an example of how you could accomplish this.

jmsTemplate.convertAndSend(ORDER_QUEUE, order, m → {
m.setJMSCorrelationID(UUID.randomUUID().toString());
m.setJMSExpiration( 1000 );
m.setBooleanProperty(SupportedProperty.SOLACE_JMS_PROP_ELIDING_ELIGIBLE, true);
return m;
}