title: Log @ConfigurationProperties in SpringBoot prior to startup?
body: <p>I'm trying to find a way to log my application properties (injected into my beans via @ConfigurationProperties) prior to the context startup so that I can see what the exact properties are before all the beans are initialized.</p>
  
  <p>I've tried to create a Listener on an ApplicationEnvironmentPreparedEvent, but there is no way to retrieve all the properties defined short of retrieving individual properties one at a time.</p>
  
  <p>Is there an easy way to do this?  Some way to initialize <code>@ConfigurationProperties</code> first and log their contents, or retrieve all the application startup properties prior to the context creation?</p>