https://logging.apache.org/log4j/2.x/log4j-core/: The Apache Log4j Implementation (The Apache Software Foundation)
  • Ralph Goers (Nextiva)
  • Gary Gregory (Rocket Software)
  • Scott Deboy
  • Remko Popma
  • Nick Williams
  • Matt Sicker (CloudBees)
  • Bruce Brouwer
  • Mikael Ståldal (Spotify)
  • Carter Kozak 
public interface org.apache.logging.log4j.core.config.plugins.validation.constraints.Required extends java.lang.annotation.Annotation
  minor version: 0
  major version: 59
  flags: flags: (0x2601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT, ACC_ANNOTATION
  this_class: org.apache.logging.log4j.core.config.plugins.validation.constraints.Required
  super_class: java.lang.Object
{
  public abstract java.lang.String message();
    descriptor: ()Ljava/lang/String;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    AnnotationDefault: "The parameter is null"
}
SourceFile: "Required.java"
    RuntimeVisibleAnnotations: 
      java.lang.annotation.Documented()
      java.lang.annotation.Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME:Ljava/lang/annotation/RetentionPolicy;)
      java.lang.annotation.Target(value = {java.lang.annotation.ElementType.FIELD:Ljava/lang/annotation/ElementType;, java.lang.annotation.ElementType.PARAMETER:Ljava/lang/annotation/ElementType;})
      org.apache.logging.log4j.core.config.plugins.validation.Constraint(value = Lorg/apache/logging/log4j/core/config/plugins/validation/validators/RequiredValidator;)