[C#] Missing fields and properties on csharp and csharp-dotnet2 generated subclasses using "allOf"

Description

If I use "allOf" in the schema I have a wrong classes export when I use the on-line editor and I generate client code for:

• csharp
• csharp-dotnet2

The exported .cs code has the subclasses, but on subclasses the filed/properties of sublasses are missing.

Swagger-codegen version

I use the codegen embedded on

Swagger declaration file content or url

definitions:
  Error:
    type: object
    properties:
      code:
        type: integer
        format: int32
      type:
        type: string
      message:
        type: string
  FieldValidationError:
    type: object
    properties:
      code:
        type: integer
        format: int32
      field:
        type: string
      message:
        type: string
  ValidationError:
    allOf:
      - $ref: '#/definitions/Error'
    type: object
    properties:
      fieldsValidationErrors:
        type: array
        items:
          $ref: '#/definitions/FieldValidationError'

Steps to reproduce

Go to , in definitions copy the YAML, go to "Generate Client" an try to export csharp.
Look at generated class ValidationError

Related issues/PRs

Suggest a fix/enhancement

The class actually generated is like:

    /// <summary>
    /// ValidationError
    /// </summary>
    [DataContract]
    public partial class ValidationError : Error,  IEquatable<ValidationError>, IValidatableObject
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="ValidationError" /> class.
        /// </summary>
        public ValidationError(int? Code = default(int?), string Type = default(string), string Message = default(string)) : base(Code, Type, Message)
        {
        }
        
        /// <summary>
        /// Returns the string presentation of the object
        /// </summary>
        /// <returns>String presentation of the object</returns>
        public override string ToString()
        {
            var sb = new StringBuilder();
            sb.Append("class ValidationError {\n");
            sb.Append("  ").Append(base.ToString().Replace("\n", "\n  ")).Append("\n");
            sb.Append("}\n");
            return sb.ToString();
        }
  
        /// <summary>
        /// Returns the JSON string presentation of the object
        /// </summary>
        /// <returns>JSON string presentation of the object</returns>
        public override string ToJson()
        {
            return JsonConvert.SerializeObject(this, Formatting.Indented);
        }

        /// <summary>
        /// Returns true if objects are equal
        /// </summary>
        /// <param name="input">Object to be compared</param>
        /// <returns>Boolean</returns>
        public override bool Equals(object input)
        {
            return this.Equals(input as ValidationError);
        }

        /// <summary>
        /// Returns true if ValidationError instances are equal
        /// </summary>
        /// <param name="input">Instance of ValidationError to be compared</param>
        /// <returns>Boolean</returns>
        public bool Equals(ValidationError input)
        {
            if (input == null)
                return false;

            return base.Equals(input);
        }

        /// <summary>
        /// Gets the hash code
        /// </summary>
        /// <returns>Hash code</returns>
        public override int GetHashCode()
        {
            unchecked // Overflow is fine, just wrap
            {
                int hashCode = base.GetHashCode();
                return hashCode;
            }
        }

        /// <summary>
        /// To validate all properties of the instance
        /// </summary>
        /// <param name="validationContext">Validation context</param>
        /// <returns>Validation Result</returns>
        IEnumerable<System.ComponentModel.DataAnnotations.ValidationResult> IValidatableObject.Validate(ValidationContext validationContext)
        {
            foreach(var x in BaseValidate(validationContext)) yield return x;
            yield break;
        }
    }

The correct one should be like:

    /// <summary>
    /// ValidationError
    /// </summary>
    [DataContract]
    public partial class ValidationError : Error,  IEquatable<ValidationError>, IValidatableObject
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="ValidationError" /> class.
        /// </summary>
        public ValidationError(int? Code = default(int?), string Type = default(string), string Message = default(string), List<FieldValidationError> FieldValidationErrors = default(List<FieldValidationError>)) : base(Code, Type, Message)
        {
            this.FieldValidationErrors = FieldValidationErrors;
        }
		
		/// <summary>
        /// Gets or Sets FieldValidationErrors
        /// </summary>
        [DataMember(Name = "fieldsValidationError", EmitDefaultValue = false)]
        public List<FieldValidationError> FieldValidationErrors { get; set; }
        
        /// <summary>
        /// Returns the string presentation of the object
        /// </summary>
        /// <returns>String presentation of the object</returns>
        public override string ToString()
        {
            var sb = new StringBuilder();
            sb.Append("class ValidationError {\n");
            sb.Append("  ").Append(base.ToString().Replace("\n", "\n  ")).Append("\n");
			sb.Append("  ").Append(FieldValidationErrors).Append("\n");
            sb.Append("}\n");
            return sb.ToString();
        }
  
        /// <summary>
        /// Returns the JSON string presentation of the object
        /// </summary>
        /// <returns>JSON string presentation of the object</returns>
        public override string ToJson()
        {
            return JsonConvert.SerializeObject(this, Formatting.Indented);
        }

        /// <summary>
        /// Returns true if objects are equal
        /// </summary>
        /// <param name="input">Object to be compared</param>
        /// <returns>Boolean</returns>
        public override bool Equals(object input)
        {
            return this.Equals(input as ValidationError);
        }

        /// <summary>
        /// Returns true if ValidationError instances are equal
        /// </summary>
        /// <param name="input">Instance of ValidationError to be compared</param>
        /// <returns>Boolean</returns>
        public bool Equals(ValidationError input)
        {
            if (input == null)
                return false;

            return base.Equals(input) &&
                (
                    this.FieldValidationErrors == input.FieldValidationErrors ||
                    this.FieldValidationErrors != null &&
                    this.FieldValidationErrors.SequenceEqual(input.FieldValidationErrors)
                );
        }

        /// <summary>
        /// Gets the hash code
        /// </summary>
        /// <returns>Hash code</returns>
        public override int GetHashCode()
        {
            unchecked // Overflow is fine, just wrap
            {
                int hashCode = base.GetHashCode();
                if (this.FieldValidationErrors != null)
                    hashCode = hashCode * 59 + this.FieldValidationErrors.GetHashCode();				
                return hashCode;
            }
        }

        /// <summary>
        /// To validate all properties of the instance
        /// </summary>
        /// <param name="validationContext">Validation context</param>
        /// <returns>Validation Result</returns>
        IEnumerable<System.ComponentModel.DataAnnotations.ValidationResult> IValidatableObject.Validate(ValidationContext validationContext)
        {
            foreach(var x in BaseValidate(validationContext)) yield return x;
            yield break;
        }
    }

Start at the online editor's Generate Client entry point and reproduce the issue with the YAML declaration in the report for csharp and csharp-dotnet2. Inspect the generated ValidationError class and the generator path responsible for allOf subclasses. Done means fieldsValidationErrors is emitted with its constructor, property, serialization, equality, hash-code, and string-output handling.