title: Set hibernate.id.new_generator_mappings in application.yaml
body: <p>I am trying to set the hibernate.id.new_generator_mappings property in order to use SequenceStyleGenerator, as I'm getting deprecation warnings for SequenceHiLoGenerator after upgrading to Spring Boot 1.4.0.RELEASE.</p>
  
  <p>I tried adding the following entry to application.yaml but it has no effect:</p>
  
  <pre><code>spring:
    jpa:
      hibernate:
        id:
          new_generator_mappings: true
  </code></pre>
  
  <p>I also tried converting to application.properties file:</p>
  
  <pre><code>spring.jpa.hibernate.id.new_generator_mappings=true
  </code></pre>
  
  <p>Stepping through the <code>JpaProperties</code> class I can see where it's trying to parse the hibernate.id.new_generator_mappings property, but it is missing.</p>
  
  <p>Is this a bug in Spring Boot, or do I have something configured incorrectly?</p>