title: No @NotBlank validator for type String
body: <p>I keep getting validator error for quite simple configuration class</p>
  
  <pre><code>import lombok.Data;
  import org.springframework.boot.context.properties.ConfigurationProperties;
  import org.springframework.stereotype.Component;
  import org.springframework.validation.annotation.Validated;
  
  import javax.validation.constraints.NotBlank;
  
  @Component
  @Data
  @Validated
  @ConfigurationProperties(prefix = "test")
  public class TestProperties {
      @NotBlank
      String uri;
  }
  </code></pre>
  
  <p>Error is self explaining:</p>
  
  <pre><code>javax.validation.UnexpectedTypeException: HV000030: No validator could be found for constraint 'javax.validation.constraints.NotBlank' validating type 'java.lang.String'. Check configuration for 'uri'
  </code></pre>
  
  <p>But according to spring boot documentation this should work.</p>