System.ComponentModel.TypeDescriptor.CreateAssociation C# (CSharp) Method

        public static void CreateAssociation(object primary, object secondary)
        {
            if (primary == null)
            {
                throw new ArgumentNullException(nameof(primary));
            }

            if (secondary == null)
            {
                throw new ArgumentNullException(nameof(secondary));
            }

            if (primary == secondary)
            {
                throw new ArgumentException(SR.TypeDescriptorSameAssociation);
            }

            if (s_associationTable == null)
            {
                lock (s_internalSyncObject)
                {
                    if (s_associationTable == null)
                    {
                        s_associationTable = new WeakHashtable();
                    }
                }
            }

            IList associations = (IList)s_associationTable[primary];

            if (associations == null)
            {
                lock (s_associationTable)
                {
                    associations = (IList)s_associationTable[primary];
                    if (associations == null)
                    {
                        associations = new ArrayList(4);
                        s_associationTable.SetWeak(primary, associations);
                    }
                }
            }
            else
            {
                for (int idx = associations.Count - 1; idx >= 0; idx--)
                {
                    WeakReference r = (WeakReference)associations[idx];
                    if (r.IsAlive && r.Target == secondary)
                    {
                        throw new ArgumentException(SR.TypeDescriptorAlreadyAssociated);
                    }
                }
            }

            lock (associations)
            {
                associations.Add(new WeakReference(secondary));
            }
        }