Fixed a few nullability issues

Author: synercoder

src/Synercoding.Primitives/Point.cs

@@ -71,10 +71,8 @@ public override int GetHashCode()
             => HashCode.Combine(X, Y);
 
         /// <inheritdoc />
-        public override bool Equals(object obj)
-        {
-            return obj is Point unit && Equals(unit);
-        }
+        public override bool Equals(object? obj)
+            => obj is Point unit && Equals(unit);
 
         /// <inheritdoc />
         public bool Equals(Point other)

src/Synercoding.Primitives/Rectangle.cs

@@ -143,10 +143,8 @@ public override int GetHashCode()
             => HashCode.Combine(LLX, LLY, URX, URY);
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
-        {
-            return obj is Rectangle unit && Equals(unit);
-        }
+        public override bool Equals(object? obj)
+            => obj is Rectangle unit && Equals(unit);
 
         /// <inheritdoc/>
         public bool Equals(Rectangle other)

src/Synercoding.Primitives/Size.cs

@@ -83,10 +83,8 @@ public override int GetHashCode()
             => HashCode.Combine(Width, Height);
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
-        {
-            return obj is Size unit && Equals(unit);
-        }
+        public override bool Equals(object? obj)
+            => obj is Size unit && Equals(unit);
 
         /// <inheritdoc/>
         public bool Equals(Size other)

src/Synercoding.Primitives/Spacing.cs

@@ -105,10 +105,8 @@ public override int GetHashCode()
             => HashCode.Combine(Left, Top, Right, Bottom);
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
-        {
-            return obj is Spacing unit && Equals(unit);
-        }
+        public override bool Equals(object? obj)
+            => obj is Spacing unit && Equals(unit);
 
         /// <inheritdoc/>
         public bool Equals(Spacing other)

src/Synercoding.Primitives/Unit.cs

@@ -39,12 +39,8 @@ public override string ToString()
             => $"{Designation.Shortform()} ({PerInch} per inch)";
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
-        {
-            if (obj is Unit unit)
-                return Equals(unit);
-            return false;
-        }
+        public override bool Equals(object? obj)
+            => obj is Unit unit && Equals(unit);
 
         /// <inheritdoc/>
         public override int GetHashCode() => HashCode.Combine(PerInch, Designation);
@@ -55,21 +51,15 @@ public override bool Equals(object obj)
         /// <param name="left">The first value to compare.</param>
         /// <param name="right">The second value to compare.</param>
         /// <returns>true if left and right are equal; otherwise, false.</returns>
-        public static bool operator ==(Unit left, Unit right)
-        {
-            return left.Equals(right);
-        }
+        public static bool operator ==(Unit left, Unit right) => left.Equals(right);
 
         /// <summary>
         ///  Returns a value that indicates whether two specified <see cref="Unit"/> values are not equal.
         /// </summary>
         /// <param name="left">The first value to compare.</param>
         /// <param name="right">The second value to compare.</param>
         /// <returns>true if left and right are not equal; otherwise, false.</returns>
-        public static bool operator !=(Unit left, Unit right)
-        {
-            return !(left == right);
-        }
+        public static bool operator !=(Unit left, Unit right) => !( left == right );
 
         /// <summary>
         /// Unit for millimeters

src/Synercoding.Primitives/UnitValue.cs

@@ -48,7 +48,7 @@ public UnitValue ConvertTo(Unit unit)
         }
 
         /// <inheritdoc/>
-        public int CompareTo(object obj)
+        public int CompareTo(object? obj)
         {
             if (obj is UnitValue unitValue)
                 return CompareTo(unitValue);
@@ -74,12 +74,8 @@ public override string ToString()
             => $"{Value} {Unit.Designation.Shortform()}";
 
         /// <inheritdoc/>
-        public override bool Equals(object obj)
-        {
-            if (obj is UnitValue unit)
-                return Equals(unit);
-            return false;
-        }
+        public override bool Equals(object? obj)
+            => obj is UnitValue unit && Equals(unit);
 
         /// <inheritdoc/>
         public bool Equals(UnitValue other)