diff --git a/src/IdentityServer/Duende/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/IdentityServer/Duende/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index d798c6a5b..c8b73d619 100644
--- a/src/IdentityServer/Duende/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/IdentityServer/Duende/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,7 +13,5 @@ public class MetaData
         public DateTimeOffset? CreationDateTime { get; set; }
 
         public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-        public string AccessToken { get; set; }
     }
 }
diff --git a/src/IdentityServer/Duende/ClassifiedAds.Domain/Specifications/Specification.cs b/src/IdentityServer/Duende/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index c79ca7372..000000000
--- a/src/IdentityServer/Duende/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,121 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications
-{
-    internal sealed class IdentitySpecification<T> : Specification<T>
-    {
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            return x => true;
-        }
-    }
-
-    public abstract class Specification<T>
-    {
-        public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-        public bool IsSatisfiedBy(T entity)
-        {
-            Func<T, bool> predicate = ToExpression().Compile();
-            return predicate(entity);
-        }
-
-        public abstract Expression<Func<T, bool>> ToExpression();
-
-        public Specification<T> And(Specification<T> specification)
-        {
-            if (this == All)
-            {
-                return specification;
-            }
-
-            if (specification == All)
-            {
-                return this;
-            }
-
-            return new AndSpecification<T>(this, specification);
-        }
-
-        public Specification<T> Or(Specification<T> specification)
-        {
-            if (this == All || specification == All)
-            {
-                return All;
-            }
-
-            return new OrSpecification<T>(this, specification);
-        }
-
-        public Specification<T> Not()
-        {
-            return new NotSpecification<T>(this);
-        }
-    }
-
-    internal sealed class AndSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _left;
-        private readonly Specification<T> _right;
-
-        public AndSpecification(Specification<T> left, Specification<T> right)
-        {
-            _left = left;
-            _right = right;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-            Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-            BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-        }
-    }
-
-    internal sealed class OrSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _left;
-        private readonly Specification<T> _right;
-
-        public OrSpecification(Specification<T> left, Specification<T> right)
-        {
-            _left = left;
-            _right = right;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-            Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-            BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-        }
-    }
-
-    internal sealed class NotSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _specification;
-
-        public NotSpecification(Specification<T> specification)
-        {
-            _specification = specification;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> expression = _specification.ToExpression();
-            UnaryExpression notExpression = Expression.Not(expression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-        }
-    }
-}
diff --git a/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index d798c6a5b..c8b73d619 100644
--- a/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,7 +13,5 @@ public class MetaData
         public DateTimeOffset? CreationDateTime { get; set; }
 
         public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-        public string AccessToken { get; set; }
     }
 }
diff --git a/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Specifications/Specification.cs b/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index c79ca7372..000000000
--- a/src/IdentityServer/IdentityServer4/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,121 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications
-{
-    internal sealed class IdentitySpecification<T> : Specification<T>
-    {
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            return x => true;
-        }
-    }
-
-    public abstract class Specification<T>
-    {
-        public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-        public bool IsSatisfiedBy(T entity)
-        {
-            Func<T, bool> predicate = ToExpression().Compile();
-            return predicate(entity);
-        }
-
-        public abstract Expression<Func<T, bool>> ToExpression();
-
-        public Specification<T> And(Specification<T> specification)
-        {
-            if (this == All)
-            {
-                return specification;
-            }
-
-            if (specification == All)
-            {
-                return this;
-            }
-
-            return new AndSpecification<T>(this, specification);
-        }
-
-        public Specification<T> Or(Specification<T> specification)
-        {
-            if (this == All || specification == All)
-            {
-                return All;
-            }
-
-            return new OrSpecification<T>(this, specification);
-        }
-
-        public Specification<T> Not()
-        {
-            return new NotSpecification<T>(this);
-        }
-    }
-
-    internal sealed class AndSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _left;
-        private readonly Specification<T> _right;
-
-        public AndSpecification(Specification<T> left, Specification<T> right)
-        {
-            _left = left;
-            _right = right;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-            Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-            BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-        }
-    }
-
-    internal sealed class OrSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _left;
-        private readonly Specification<T> _right;
-
-        public OrSpecification(Specification<T> left, Specification<T> right)
-        {
-            _left = left;
-            _right = right;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-            Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-            BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-        }
-    }
-
-    internal sealed class NotSpecification<T> : Specification<T>
-    {
-        private readonly Specification<T> _specification;
-
-        public NotSpecification(Specification<T> specification)
-        {
-            _specification = specification;
-        }
-
-        public override Expression<Func<T, bool>> ToExpression()
-        {
-            Expression<Func<T, bool>> expression = _specification.ToExpression();
-            UnaryExpression notExpression = Expression.Not(expression.Body);
-
-            return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-        }
-    }
-}
diff --git a/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index 63c6cfc73..d2c0de30c 100644
--- a/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,6 +13,4 @@ public class MetaData
     public DateTimeOffset? CreationDateTime { get; set; }
 
     public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-    public string AccessToken { get; set; }
 }
diff --git a/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Specifications/Specification.cs b/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index aa9b1fefc..000000000
--- a/src/IdentityServer/OpenIddict/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,120 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications;
-
-internal sealed class IdentitySpecification<T> : Specification<T>
-{
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        return x => true;
-    }
-}
-
-public abstract class Specification<T>
-{
-    public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-    public bool IsSatisfiedBy(T entity)
-    {
-        Func<T, bool> predicate = ToExpression().Compile();
-        return predicate(entity);
-    }
-
-    public abstract Expression<Func<T, bool>> ToExpression();
-
-    public Specification<T> And(Specification<T> specification)
-    {
-        if (this == All)
-        {
-            return specification;
-        }
-
-        if (specification == All)
-        {
-            return this;
-        }
-
-        return new AndSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Or(Specification<T> specification)
-    {
-        if (this == All || specification == All)
-        {
-            return All;
-        }
-
-        return new OrSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Not()
-    {
-        return new NotSpecification<T>(this);
-    }
-}
-
-internal sealed class AndSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public AndSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-    }
-}
-
-internal sealed class OrSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public OrSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-    }
-}
-
-internal sealed class NotSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _specification;
-
-    public NotSpecification(Specification<T> specification)
-    {
-        _specification = specification;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> expression = _specification.ToExpression();
-        UnaryExpression notExpression = Expression.Not(expression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-    }
-}
diff --git a/src/Microservices/Common/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/Microservices/Common/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index 63c6cfc73..d2c0de30c 100644
--- a/src/Microservices/Common/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/Microservices/Common/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,6 +13,4 @@ public class MetaData
     public DateTimeOffset? CreationDateTime { get; set; }
 
     public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-    public string AccessToken { get; set; }
 }
diff --git a/src/Microservices/Common/ClassifiedAds.Domain/Specifications/Specification.cs b/src/Microservices/Common/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index ef5d936e2..000000000
--- a/src/Microservices/Common/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,116 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications;
-
-internal sealed class IdentitySpecification<T> : Specification<T>
-{
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        return x => true;
-    }
-}
-
-public abstract class Specification<T>
-{
-    public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-    public bool IsSatisfiedBy(T entity)
-    {
-        Func<T, bool> predicate = ToExpression().Compile();
-        return predicate(entity);
-    }
-
-    public abstract Expression<Func<T, bool>> ToExpression();
-
-    public Specification<T> And(Specification<T> specification)
-    {
-        if (this == All)
-            return specification;
-        if (specification == All)
-            return this;
-
-        return new AndSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Or(Specification<T> specification)
-    {
-        if (this == All || specification == All)
-            return All;
-
-        return new OrSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Not()
-    {
-        return new NotSpecification<T>(this);
-    }
-}
-
-
-internal sealed class AndSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public AndSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-    }
-}
-
-
-internal sealed class OrSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public OrSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-    }
-}
-
-
-internal sealed class NotSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _specification;
-
-    public NotSpecification(Specification<T> specification)
-    {
-        _specification = specification;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> expression = _specification.ToExpression();
-        UnaryExpression notExpression = Expression.Not(expression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-    }
-}
diff --git a/src/ModularMonolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/ModularMonolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index 63c6cfc73..d2c0de30c 100644
--- a/src/ModularMonolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/ModularMonolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,6 +13,4 @@ public class MetaData
     public DateTimeOffset? CreationDateTime { get; set; }
 
     public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-    public string AccessToken { get; set; }
 }
diff --git a/src/ModularMonolith/ClassifiedAds.Domain/Specifications/Specification.cs b/src/ModularMonolith/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index ef5d936e2..000000000
--- a/src/ModularMonolith/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,116 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications;
-
-internal sealed class IdentitySpecification<T> : Specification<T>
-{
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        return x => true;
-    }
-}
-
-public abstract class Specification<T>
-{
-    public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-    public bool IsSatisfiedBy(T entity)
-    {
-        Func<T, bool> predicate = ToExpression().Compile();
-        return predicate(entity);
-    }
-
-    public abstract Expression<Func<T, bool>> ToExpression();
-
-    public Specification<T> And(Specification<T> specification)
-    {
-        if (this == All)
-            return specification;
-        if (specification == All)
-            return this;
-
-        return new AndSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Or(Specification<T> specification)
-    {
-        if (this == All || specification == All)
-            return All;
-
-        return new OrSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Not()
-    {
-        return new NotSpecification<T>(this);
-    }
-}
-
-
-internal sealed class AndSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public AndSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-    }
-}
-
-
-internal sealed class OrSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public OrSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-    }
-}
-
-
-internal sealed class NotSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _specification;
-
-    public NotSpecification(Specification<T> specification)
-    {
-        _specification = specification;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> expression = _specification.ToExpression();
-        UnaryExpression notExpression = Expression.Not(expression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-    }
-}
diff --git a/src/Monolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs b/src/Monolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
index 63c6cfc73..d2c0de30c 100644
--- a/src/Monolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
+++ b/src/Monolith/ClassifiedAds.Domain/Infrastructure/MessageBrokers/MetaData.cs
@@ -13,6 +13,4 @@ public class MetaData
     public DateTimeOffset? CreationDateTime { get; set; }
 
     public DateTimeOffset? EnqueuedDateTime { get; set; }
-
-    public string AccessToken { get; set; }
 }
diff --git a/src/Monolith/ClassifiedAds.Domain/Specifications/Specification.cs b/src/Monolith/ClassifiedAds.Domain/Specifications/Specification.cs
deleted file mode 100644
index aa9b1fefc..000000000
--- a/src/Monolith/ClassifiedAds.Domain/Specifications/Specification.cs
+++ /dev/null
@@ -1,120 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using System.Text;
-
-namespace ClassifiedAds.Domain.Specifications;
-
-internal sealed class IdentitySpecification<T> : Specification<T>
-{
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        return x => true;
-    }
-}
-
-public abstract class Specification<T>
-{
-    public static readonly Specification<T> All = new IdentitySpecification<T>();
-
-    public bool IsSatisfiedBy(T entity)
-    {
-        Func<T, bool> predicate = ToExpression().Compile();
-        return predicate(entity);
-    }
-
-    public abstract Expression<Func<T, bool>> ToExpression();
-
-    public Specification<T> And(Specification<T> specification)
-    {
-        if (this == All)
-        {
-            return specification;
-        }
-
-        if (specification == All)
-        {
-            return this;
-        }
-
-        return new AndSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Or(Specification<T> specification)
-    {
-        if (this == All || specification == All)
-        {
-            return All;
-        }
-
-        return new OrSpecification<T>(this, specification);
-    }
-
-    public Specification<T> Not()
-    {
-        return new NotSpecification<T>(this);
-    }
-}
-
-internal sealed class AndSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public AndSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression andExpression = Expression.AndAlso(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(andExpression, leftExpression.Parameters.Single());
-    }
-}
-
-internal sealed class OrSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _left;
-    private readonly Specification<T> _right;
-
-    public OrSpecification(Specification<T> left, Specification<T> right)
-    {
-        _left = left;
-        _right = right;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> leftExpression = _left.ToExpression();
-        Expression<Func<T, bool>> rightExpression = _right.ToExpression();
-
-        BinaryExpression orExpression = Expression.OrElse(leftExpression.Body, rightExpression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(orExpression, leftExpression.Parameters.Single());
-    }
-}
-
-internal sealed class NotSpecification<T> : Specification<T>
-{
-    private readonly Specification<T> _specification;
-
-    public NotSpecification(Specification<T> specification)
-    {
-        _specification = specification;
-    }
-
-    public override Expression<Func<T, bool>> ToExpression()
-    {
-        Expression<Func<T, bool>> expression = _specification.ToExpression();
-        UnaryExpression notExpression = Expression.Not(expression.Body);
-
-        return Expression.Lambda<Func<T, bool>>(notExpression, expression.Parameters.Single());
-    }
-}