Spring Boot autoconfiguration conditional annotation on typesafe ConfigurationProperies class. Maps properties to the provided class and executes it's isPresent() method to determine if Conditional should match or not. application.yml, ExampleSpringConfiguration.java and ExampleSpringPropertiesModel.java show how the rest of the code can be used.

application.yml

your:
  properties:
    prefix:
      example-configuration-property: 'foobar'

ConditionalOnConfigurationProperties.java

/**
 * Metannotation for OnConfigurationPropertiesCondition custom conditional implementation.
 */
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional(OnConfigurationPropertiesCondition.class)
public @interface ConditionalOnConfigurationProperties {

  // properties namespace
  String prefix();

  // configuration properties model class
  Class<? extends OptionalProperties> targetClass();
  
}

ExampleSpringConfiguration.java

@Configuration
public class ExampleSpringConfiguration {
  
  @Bean
  @ConditionalOnConfigurationProperties(prefix = ExampleSpringPropertiesModel.PREFIX, targetClass = ExampleSpringPropertiesModel.class)
  @ConditionalOnMissingBean
  YourType provideDefaultElementOfTheSystem(ExampleSpringPropertiesModel properties) {
    // this bean factory method will be invoked only if there is no bean of 'YourType' defined elsewhere
    // and properties in application.yml are provided
    // then you can construct a bean based on the properties
    // great for autoconfiguration (spring-boot-starter like modules)
  }
  
}

ExampleSpringPropertiesModel.java

@ConfigurationProperties(ExampleSpringPropertiesModel.PREFIX)
@ConstructorBinding
@RequiredArgsConstructor
@Getter
public class ExampleSpringPropertiesModel implements OptionalProperties {

  public static final String PREFIX = "your.properties.prefix";

  private final String exampleConfigurationProperty;

  @Override
  public boolean isPresent() {
    return exampleConfigurationProperty != null;
  }

}

OnConfigurationPropertiesCondition.java

/**
 * Custom conditional that checks if properties required by the targetClass
 * are present in the {@link Environment}.
 *
 * targetClass must implement the {@link OptionalProperties} interface in order to define custom logic
 * checking if properties are in fact set.
 *
 * Condition will not match if any of the following statements is true:
 * <ul>
 *   <li>{@link org.springframework.boot.context.properties.bind.Binder Binder} could not bind properties to the target type</li>
 *   <li>Target class instance was successfully bound but {@link OptionalProperties#isPresent()} returned false</li>
 * </ul>
 *
 */
public class OnConfigurationPropertiesCondition extends SpringBootCondition {

  @Override
  public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
    MergedAnnotation<ConditionalOnConfigurationProperties> mergedAnnotation = metadata.getAnnotations().get(ConditionalOnConfigurationProperties.class);
    String prefix = mergedAnnotation.getString("prefix");
    Class<?> targetClass = mergedAnnotation.getClass("targetClass");
    if (!OptionalProperties.class.isAssignableFrom(targetClass)) {
      return ConditionOutcome.noMatch("Target type does not implement the OptionalProperties interface.");
    }
    Object bean = Binder.get(context.getEnvironment()).bind(prefix, targetClass).orElse(null);
    if (bean == null) {
      return ConditionOutcome.noMatch("Binding properties to target type resulted in null value.");
    }
    OptionalProperties props = (OptionalProperties) bean;
    if (props.isPresent()) {
      return ConditionOutcome.match();
    } else {
      return ConditionOutcome.noMatch("Properties are not present.");
    }
  }

}

OptionalProperties.java

/**
 * Allows defining custom logic to check if configuration model class is in fact filled with data.
 */
public interface OptionalProperties {

  boolean isPresent();

}

Could you provide an example to how to use it?

@Mazzotta13 Added ExampleSpringConfiguration.java, ExampleSpringPropertiesModel.java and application.yml to show how it can all be used together.