title: spring-boot 2.3.6, how to set UUID representation for mongo?
body: <p>I'm trying to upgrade to spring-boot 2.3.6. I'm using spring-data MongoRepositories, no difrect calls to MongoClient or MongoClient.</p>
  <p>Getting exception:</p>
  <pre><code>Caused by: org.bson.codecs.configuration.CodecConfigurationException: The uuidRepresentation has not been specified, so the UUID cannot be encoded.
      at org.bson.codecs.UuidCodec.encode(UuidCodec.java:72)
      at org.bson.codecs.UuidCodec.encode(UuidCodec.java:37)
      at org.bson.codecs.EncoderContext.encodeWithChildContext(EncoderContext.java:91)
      at org.bson.codecs.DocumentCodec.writeValue(DocumentCodec.java:198)
      at org.bson.codecs.DocumentCodec.writeMap(DocumentCodec.java:212)
      at org.bson.codecs.DocumentCodec.encode(DocumentCodec.java:154)
      at org.bson.codecs.DocumentCodec.encode(DocumentCodec.java:45)
  
  </code></pre>
  <p>Tried to customize</p>
  <pre class="lang-java prettyprint-override"><code>@Bean
      public MongoClientSettingsBuilderCustomizer mongoDBDefaultSettings() {
          return builder -&gt; {
              builder.uuidRepresentation(UuidRepresentation.JAVA_LEGACY);
          };
      }
  </code></pre>
  <p>doesn't help, same exception.</p>
  <p>What is the right way to customize UUID codec in spring-boot 2.3.6?</p>
  <p>Thank you.</p>