anchor.diff:  
   In order to validate values of nested properties, you must annotate the associated field
   as `@Valid` to trigger its validation. For example, building upon the above
  -`ConnectionSettings` example:
  -
  -[source,java,indent=0]
  -----
  -	@Component
  +`ConnectionProperties` example:
  +
  +[source,java,indent=0]
  +----
   	@ConfigurationProperties(prefix="connection")
  -	public class ConnectionSettings {
  +	public class ConnectionProperties {
   
   		@NotNull
   		@Valid
  
positive.code: 
  [source,java,indent=0]
  ----
  	@Component
  	@ConfigurationProperties(prefix="person")
  	public class ConnectionSettings {
  
  		private String firstName;
  
  
negative.code: TIP: See also the <<boot-features-external-config-vs-value,differences between `@Value`
  and `@ConfigurationProperties`>>.
  
  You also need to list the properties classes to register in the
  `@EnableConfigurationProperties` annotation:
  
  [source,java,indent=0]
  ----
  	@Configuration
  	@EnableConfigurationProperties(ConnectionProperties.class)
  	public class MyConfiguration {
  	}
  ----
  