public interface StageConfigurer {
  ....

  /**
   * AddsReturns causea attributesfailure thatcollector representsfor plugin not found failure causethe stage.
   *
   * @param@return pluginIda pluginfailure idcollector
   * @param@throws pluginNameUnsupportedOperationException pluginif namethe implementation does not *override @paramthis pluginTypemethod
plugin type  */
 *  default FailureCollector getFailureCollector() {
    throw new UnsupportedOperationException("Getting failure collector is not supported.");
  }
}

/**
 * Validation exception that carries multiple validation failures.
 */
@Beta
public class ValidationException extends RuntimeException {
  private final List<ValidationFailure> failures;

  /**
   * Creates a validation exception with list of failures.
   *
   * @param failures list of validation failures
   */
  public ValidationException(List<ValidationFailure> failures) {
    super("Errors were encountered during validation.");
    this.failures = Collections.unmodifiableList(new ArrayList<>(failures));
  }

  /**
   * Returns a list of validation failures.
   */
  public List<ValidationFailure> getFailures() {
    return failures;
  }
}

/**
 * Represents a failure condition occurred during validation.
 */
@Beta
public class ValidationFailure {
  private static final Gson GSON = new Gson();
  private final String message;
  private final String correctiveAction;
  private final List<Cause> causes;

  /**
   * Creates a validation failure with provided message.
   *
   * @param message validation failure message
   */
  public ValidationFailure(String message) {
    this(message, null);
  }

  /**
   * Creates a validation failure with provided message and corrective action.
   *
   * @param message validation failure message
   * @param correctiveAction corrective action
   */
  public ValidationFailure(String message, @Nullable String correctiveAction) {
    this.message = message;
    this.correctiveAction = correctiveAction;
    this.causes = new ArrayList<>();
  }

  /**
   * Adds provided cause to this validation failure.
   *
   * @param cause cause of validation failure
   * @return validation failure with provided cause
   */
  public ValidationFailure withCause(Cause cause) {
    causes.add(cause);
    return this;
  }

  /**
   * Adds cause attributes that represents plugin not found failure cause.
   *
   * @param pluginId plugin id
   * @param pluginName plugin name
   * @param pluginType plugin type
   * @return validation failure with plugin not found cause
   */
  public ValidationFailure withPluginNotFound(String pluginId, String pluginName, String pluginType) {
    return withPluginNotFound(pluginId, pluginName, pluginType, null, null);
  }

  /**
   * Adds cause attributes that represents plugin not found failure cause.
   *
   * @param pluginId plugin id
   * @param pluginName plugin name
   * @param pluginType plugin type
   * @param requestedArtifact requested artifact
   * @param suggestedArtifact suggested artifact
   * @return validation failure with plugin not found cause
   */
  public ValidationFailure withPluginNotFound(String pluginId, String pluginName, String pluginType,
                                              @Nullable ArtifactId requestedArtifact,
                                              @Nullable ArtifactId suggestedArtifact) {
    Cause cause = new Cause().addAttribute(CauseAttributes.PLUGIN_ID, pluginId)
      .addAttribute(CauseAttributes.PLUGIN_NAME, pluginName)
      .addAttribute(CauseAttributes.PLUGIN_TYPE, pluginType);
    if (requestedArtifact != null) {
      cause.addAttribute(CauseAttributes.REQUESTED_ARTIFACT_NAME, requestedArtifact.getName());
      cause.addAttribute(CauseAttributes.REQUESTED_ARTIFACT_SCOPE, requestedArtifact.getScope().name());
      cause.addAttribute(CauseAttributes.REQUESTED_ARTIFACT_VERSION, requestedArtifact.getVersion().getVersion());
    }

    if (suggestedArtifact != null) {
      cause.addAttribute(CauseAttributes.SUGGESTED_ARTIFACT_NAME, suggestedArtifact.getName());
      cause.addAttribute(CauseAttributes.SUGGESTED_ARTIFACT_SCOPE, suggestedArtifact.getScope().name());
      cause.addAttribute(CauseAttributes.SUGGESTED_ARTIFACT_VERSION, suggestedArtifact.getVersion().getVersion());
    }
    causes.add(cause);
    return this;
  }

  /**
   * Adds cause attributes that represents invalid stage configure property failure cause.
   *
   * @param stageConfigProperty stage config property
   * @return validation failure with invalid stage config property cause
   */
  public ValidationFailure withConfigProperty(String stageConfigProperty) {
    causes.add(new Cause().addAttribute(CauseAttributes.STAGE_CONFIG, stageConfigProperty));
    return this;
  }

  /**
   * Adds cause attributes for failure cause that represents an invalid element in the list associated with given stage
   * configure property.
   *
   * @param stageConfigProperty stage config property
   * @param element element in the list associated by a given stageConfigProperty
   * @return validation failure with invalid stage config property element cause
   */
  public ValidationFailure withConfigElement(String stageConfigProperty, String element) {
    causes.add(new Cause().addAttribute(CauseAttributes.STAGE_CONFIG, stageConfigProperty)
                 .addAttribute(CauseAttributes.CONFIG_ELEMENT, element));
    return this;
  }

  /**
   * Adds cause attributes that represents invalid input schema field failure cause.
   *
   * @param fieldName name of the input schema field
   * @param inputStage stage name
   * @return validation failure with invalid input schema field cause
   */
  public ValidationFailure withInputSchemaField(String fieldName, @Nullable String inputStage) {
    Cause cause = new Cause().addAttribute(CauseAttributes.INPUT_SCHEMA_FIELD, fieldName);
    cause = inputStage == null ? cause : cause.addAttribute(CauseAttributes.INPUT_STAGE, inputStage);
    causes.add(cause);
    return this;
  }

  /**
   * Adds cause attributes that represents invalid output schema field failure cause.
   *
   * @param fieldName name of the output schema field
   * @param outputPort stage name
   * @return validation failure with plugininvalid output notschema foundfield cause
   */
  public ValidationFailure withPluginNotFoundCausewithOutputSchemaField(String pluginIdfieldName, String pluginName,@Nullable String pluginTypeoutputPort) {
     causes.add(Cause cause = new Cause().withaddAttribute(CauseAttributes.PLUGIN_ID, pluginId).with(CauseAttributes.PLUGIN_NAME, pluginName)OUTPUT_SCHEMA_FIELD, fieldName);
    cause = outputPort == null ? cause :      .withcause.addAttribute(CauseAttributes.PLUGINOUTPUT_TYPEPORT, pluginType)outputPort);
    causes.add(cause);
    return this;
  }

  /**
   * Adds cause attributes that represents plugin configure failure causea stacktrace.
   *
   * @param stacktraceElements pluginConfigstacktrace pluginfor configthe propertyerror
   * @return validation failure with invalid plugin config property causestacktrace
   */
  public ValidationFailure withPluginConfigCausewithStacktrace(StringStackTraceElement[] pluginConfigstacktraceElements) {
    causes.add(new Cause().withaddAttribute(CauseAttributes.PLUGIN_CONFIGSTACKTRACE, pluginConfigGSON.toJson(stacktraceElements)));
    return this;
  }

  /**
   * Adds cause attributes that represents invalid input schema field failure causeReturns failure message.
   */
  public *String @paramgetMessage() fieldName{
name of the input schemareturn fieldmessage;
  }
*
@param inputStage stage name /**
   * @returnReturns validationcorrective failureaction withfor invalidthis inputfailure.
schema field cause */
  */@Nullable
  public ValidationFailureString withInvalidInputSchemaCausegetCorrectiveAction(String) {
fieldName, @Nullable String inputStage) {return correctiveAction;
  }
causes.add(new
Cause().with(CauseAttributes.INPUT_STAGE, inputStage) /**
   * Returns causes that caused this failure.
   */
  .with(CauseAttributes.INPUT_SCHEMA_FIELD, fieldName));public List<Cause> getCauses() {
    return thiscauses;
  }

  @Override
  public boolean equals(Object o) /**{
   * Addsif cause(this attributes== thato) represents{
invalid output schema field failure cause. return true;
 *   }
* @param fieldName name ofif the(o output== schemanull field|| getClass() !=  * @param outputPort stage nameo.getClass()) {
      return *false;
@return validation failure with invalid}
output schema field cause ValidationFailure failure = */
(ValidationFailure) o;
 public ValidationFailure withInvalidOutputSchemaCause(String fieldName, @Nullable String outputPort) {return message.equals(failure.message) &&
      causesObjects.add(new Cause().with(CauseAttributes.OUTPUT_PORT, outputPort)
 equals(correctiveAction, failure.correctiveAction) && causes.equals(failure.causes);
  }

  @Override
  public int hashCode() {
    return Objects.with(CauseAttributes.OUTPUT_SCHEMA_FIELD, fieldName))hash(message, correctiveAction, causes);
  }

return this;
  } /**
   /** Represents a cause *of Returnsa failure message.
   */
  @Beta
  public String getMessage()static class Cause {
    return message private final Map<String, String> attributes;

 }    /**
     * ReturnsCreates correctivea actionfailure forcause.
this failure.    */
  @Nullable   public String getCorrectiveActionCause() {
      this.attributes = returnnew correctiveActionHashMap<>();
    }

    /**
     * ReturnsAdds causesan thatattribute causedto this failurecause.
   */  *
public List<Cause> getCauses() {  * @param attribute returncause causes;attribute name
 }    @Override* @param value publiccause booleanattribute equals(Objectvalue
o) {    * if@return (this ==cause
o) {    */
  return true; public Cause addAttribute(String attribute, }String value) {
  if (o == null || getClass() != o.getClass()) { attributes.put(attribute, value);
      return falsethis;
    }

    /**
 ValidationFailure  failure = (ValidationFailure) o;
    return message.equals(failure.message) &&* Returns value of the provided cause attribute.
     *
     *  Objects.equals(correctiveAction, failure.correctiveAction) && causes.equals(failure.causes);@param attribute attribute name
   }  */
 @Override   public intString hashCodegetAttribute(String attribute) {
      return Objectsattributes.hash(message, correctiveAction, causes);get(attribute);
    }

    /***
     * Returns Representsall athe causeattributes of athe failurecause.
     */

 @Beta   public staticMap<String, classString> CausegetAttributes() {
    private final Map<String, String> attributesreturn Collections.unmodifiableMap(new HashMap<>(attributes));
    }
/**
    @Override
* Creates a failure cause.public boolean equals(Object o) {
 */     publicif Cause(this == o) {
      this.attributes = newreturn HashMap<>()true;
      }
      if (o ==  /**
null || getClass() != o.getClass()) {
    * Adds attributes to thisreturn cause.false;
     * }
    * @param attributeCause cause attribute= name(Cause) o;
    * @param valuereturn attributes.equals(cause.attributes);
attribute value   }

 * @return this cause@Override
     */
    public Causeint with(String attribute, String valuehashCode() {
      attributesreturn Objects.put(attribute, valuehash(attributes);
     }
return this;     }

    }
}

/**
 * Cause attributes constants.
 */
Returns@Beta
causepublic attributes.class CauseAttributes {

  *// Represents stage configuration property publicfailure
Map<String, String> getAttributes()public {static final String STAGE_CONFIG    return attributes= "stageConfig";
  // Represents }an element in the list of @Overrideelements associated with a stage publicconfig booleanproperty.
equals(Object o) {// For example, in    if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }
      Cause cause = (Cause) o;
      return attributes.equals(cause.attributes);
    }

    @Override
    public int hashCode() {
      return Objects.hash(attributes);
    }
  }
}