Change IccProfileSequenceIdentifier to a struct

src/ImageSharp/MetaData/Profiles/ICC/DataWriter/IccDataWriter.TagDataEntry.cs

@@ -709,13 +709,15 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
             // Jump over position table
             long tablePosition = this.dataStream.Position;
             this.dataStream.Position += length * 8;
-            IccPositionNumber[] table = new IccPositionNumber[length];
+            var table = new IccPositionNumber[length];
 
             for (int i = 0; i < length; i++)
             {
+                ref IccProfileSequenceIdentifier sequenceIdentifier = ref value.Data[i];
+
                 uint offset = (uint)(this.dataStream.Position - start);
-                int size = this.WriteProfileId(value.Data[i].Id);
-                size += this.WriteTagDataEntry(new IccMultiLocalizedUnicodeTagDataEntry(value.Data[i].Description));
+                int size = this.WriteProfileId(sequenceIdentifier.Id);
+                size += this.WriteTagDataEntry(new IccMultiLocalizedUnicodeTagDataEntry(sequenceIdentifier.Description));
                 size += this.WritePadding();
                 table[i] = new IccPositionNumber(offset, (uint)size);
                 count += size;

src/ImageSharp/MetaData/Profiles/ICC/TagDataEntries/IccProfileSequenceIdentifierTagDataEntry.cs

@@ -41,8 +41,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         /// <inheritdoc/>
         public override bool Equals(IccTagDataEntry other)
         {
-            var entry = other as IccProfileSequenceIdentifierTagDataEntry;
-            return entry != null && this.Equals(entry);
+            return other is IccProfileSequenceIdentifierTagDataEntry entry && this.Equals(entry);
         }
 
         /// <inheritdoc />
@@ -74,7 +73,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
                 return true;
             }
 
-            return obj is IccProfileSequenceIdentifierTagDataEntry && this.Equals((IccProfileSequenceIdentifierTagDataEntry)obj);
+            return obj is IccProfileSequenceIdentifierTagDataEntry other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/MetaData/Profiles/ICC/Various/IccProfileSequenceIdentifier.cs

@@ -7,12 +7,12 @@ using System.Linq;
 namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
 {
     /// <summary>
-    /// Description of a profile within a sequence
+    /// Description of a profile within a sequence.
     /// </summary>
-    internal sealed class IccProfileSequenceIdentifier : IEquatable<IccProfileSequenceIdentifier>
+    internal readonly struct IccProfileSequenceIdentifier : IEquatable<IccProfileSequenceIdentifier>
     {
         /// <summary>
-        /// Initializes a new instance of the <see cref="IccProfileSequenceIdentifier"/> class.
+        /// Initializes a new instance of the <see cref="IccProfileSequenceIdentifier"/> struct.
         /// </summary>
         /// <param name="id">ID of the profile</param>
         /// <param name="description">Description of the profile</param>
@@ -25,44 +25,23 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         }
 
         /// <summary>
-        /// Gets the ID of the profile
+        /// Gets the ID of the profile.
         /// </summary>
         public IccProfileId Id { get; }
 
         /// <summary>
-        /// Gets the description of the profile
+        /// Gets the description of the profile.
         /// </summary>
         public IccLocalizedString[] Description { get; }
 
         /// <inheritdoc />
-        public bool Equals(IccProfileSequenceIdentifier other)
-        {
-            if (ReferenceEquals(null, other))
-            {
-                return false;
-            }
-
-            if (ReferenceEquals(this, other))
-            {
-                return true;
-            }
-
-            return this.Id.Equals(other.Id) && this.Description.SequenceEqual(other.Description);
-        }
+        public bool Equals(IccProfileSequenceIdentifier other) =>
+            this.Id.Equals(other.Id) &&
+            this.Description.SequenceEqual(other.Description);
 
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            if (obj == null)
-            {
-                return false;
-            }
-
-            if (ReferenceEquals(this, obj))
-            {
-                return true;
-            }
-
             return obj is IccProfileSequenceIdentifier other && this.Equals(other);
         }