Removed all nullable code until it's turned on.

src/CsvHelper/Configuration/Attributes/HeaderPrefixAttribute.cs

@@ -15,7 +15,7 @@ public class HeaderPrefixAttribute : Attribute, IMemberReferenceMapper, IParamet
 		/// <summary>
 		/// Gets the prefix.
 		/// </summary>
-		public string? Prefix { get; private set; }
+		public string Prefix { get; private set; }
 
 		/// <summary>
 		/// Gets a value indicating if the prefix should inherit parent prefixes.

src/CsvHelper/Configuration/ClassMapCollection.cs

@@ -25,7 +25,7 @@ public class ClassMapCollection
 		/// </value>
 		/// <param name="type">The record type.</param>
 		/// <returns>The <see cref="ClassMap"/> for the specified record type.</returns>
-		public virtual ClassMap? this[Type type]
+		public virtual ClassMap this[Type type]
 		{
 			get
 			{
@@ -63,9 +63,9 @@ public ClassMapCollection(CsvContext context)
 		/// </summary>
 		/// <typeparam name="T">The record type.</typeparam>
 		/// <returns>The <see cref="ClassMap"/> for the specified record type.</returns>
-		public virtual ClassMap<T>? Find<T>()
+		public virtual ClassMap<T> Find<T>()
 		{
-			return (ClassMap<T>?)this[typeof(T)];
+			return (ClassMap<T>)this[typeof(T)];
 		}
 
 		/// <summary>

src/CsvHelper/Configuration/ConfigurationFunctions.cs

@@ -180,7 +180,7 @@ public static string GetDynamicPropertyName(GetDynamicPropertyNameArgs args)
 		/// Return the detected delimiter or null if one wasn't found.
 		/// </summary>
 		/// <param name="args">The args.</param>
-		public static string? GetDelimiter(GetDelimiterArgs args)
+		public static string GetDelimiter(GetDelimiterArgs args)
 		{
 			var text = args.Text;
 			var config = args.Configuration;
@@ -244,7 +244,7 @@ orderby sum descending
 				}
 			).ToList();
 
-			string? newDelimiter = null;
+			string newDelimiter = null;
 			if (delimiters.Any(x => x.Delimiter == config.CultureInfo.TextInfo.ListSeparator) && lineDelimiterCounts.Count > 1)
 			{
 				// The culture's separator is on every line. Assume this is the delimiter.

src/CsvHelper/Configuration/CsvConfiguration.cs

@@ -59,7 +59,7 @@ public record CsvConfiguration : IReaderConfiguration, IWriterConfiguration
 		public virtual bool DetectColumnCountChanges { get; set; }
 
 		/// <inheritdoc/>
-		public virtual IComparer<string>? DynamicPropertySort { get; set; }
+		public virtual IComparer<string> DynamicPropertySort { get; set; }
 
 		/// <inheritdoc/>
 		public virtual Encoding Encoding { get; set; } = Encoding.UTF8;
@@ -142,13 +142,13 @@ public virtual string NewLine
 		public virtual ReadingExceptionOccurred ReadingExceptionOccurred { get; set; } = ConfigurationFunctions.ReadingExceptionOccurred;
 
 		/// <inheritdoc/>
-		public virtual ReferenceHeaderPrefix? ReferenceHeaderPrefix { get; set; }
+		public virtual ReferenceHeaderPrefix ReferenceHeaderPrefix { get; set; }
 
 		/// <inheritdoc/>
 		public ShouldQuote ShouldQuote { get; set; } = ConfigurationFunctions.ShouldQuote;
 
 		/// <inheritdoc/>
-		public virtual ShouldSkipRecord? ShouldSkipRecord { get; set; }
+		public virtual ShouldSkipRecord ShouldSkipRecord { get; set; }
 
 		/// <inheritdoc/>
 		public virtual ShouldUseConstructorParameters ShouldUseConstructorParameters { get; set; } = ConfigurationFunctions.ShouldUseConstructorParameters;
@@ -171,7 +171,7 @@ public virtual string NewLine
 		/// <param name="cultureInfo">The culture information.</param>
 		/// <param name="attributesType">The type that contains the configuration attributes.
 		/// This will call <see cref="ApplyAttributes(Type)"/> automatically.</param>
-		public CsvConfiguration(CultureInfo cultureInfo, Type? attributesType = null)
+		public CsvConfiguration(CultureInfo cultureInfo, Type attributesType = null)
 		{
 			CultureInfo = cultureInfo;
 			Delimiter = cultureInfo.TextInfo.ListSeparator;

src/CsvHelper/Configuration/IReaderConfiguration.cs

@@ -80,7 +80,7 @@ public interface IReaderConfiguration : IParserConfiguration
 		/// Gets the callback that will be called to
 		/// determine whether to skip the given record or not.
 		/// </summary>
-		ShouldSkipRecord? ShouldSkipRecord { get; }
+		ShouldSkipRecord ShouldSkipRecord { get; }
 
 		/// <summary>
 		/// Gets a value indicating if private

src/CsvHelper/Configuration/MemberMap.cs

@@ -129,7 +129,7 @@ public virtual MemberMap Ignore(bool ignore)
 		/// </summary>
 		/// <param name="defaultValue">The default value.</param>
 		/// <param name="useOnConversionFailure">Use default on conversion failure.</param>
-		public virtual MemberMap Default(object? defaultValue, bool useOnConversionFailure = false)
+		public virtual MemberMap Default(object defaultValue, bool useOnConversionFailure = false)
 		{
 			if (defaultValue == null && Data.Member.MemberType().IsValueType)
 			{

src/CsvHelper/Configuration/MemberMapCollection.cs

@@ -203,7 +203,7 @@ public virtual MemberMap this[int index]
 		/// <typeparam name="T">The <see cref="System.Type"/> the member is on.</typeparam>
 		/// <param name="expression">The member expression.</param>
 		/// <returns>The <see cref="MemberMap"/> for the given expression, or null if not found.</returns>
-		public virtual MemberMap? Find<T>(Expression<Func<T, object>> expression)
+		public virtual MemberMap Find<T>(Expression<Func<T, object>> expression)
 		{
 			var member = ReflectionHelper.GetMember(expression);
 			return Find(member);
@@ -214,7 +214,7 @@ public virtual MemberMap this[int index]
 		/// </summary>
 		/// <param name="member">The member.</param>
 		/// <returns>The <see cref="MemberMap"/> for the given expression, or null if not found.</returns>
-		public virtual MemberMap? Find(MemberInfo member)
+		public virtual MemberMap Find(MemberInfo member)
 		{
 			var existingMap = list.SingleOrDefault(m =>
 			   m.Data.Member == member ||

src/CsvHelper/Configuration/MemberMapData.cs

@@ -44,7 +44,7 @@ public virtual Type Type
 		/// Gets the <see cref="MemberInfo"/> that the data
 		/// is associated with.
 		/// </summary>
-		public virtual MemberInfo? Member { get; private set; }
+		public virtual MemberInfo Member { get; private set; }
 
 		/// <summary>
 		/// Gets the list of column names.
@@ -87,7 +87,7 @@ public virtual Type Type
 		/// <summary>
 		/// Gets or sets the type converter.
 		/// </summary>
-		public virtual ITypeConverter? TypeConverter { get; set; }
+		public virtual ITypeConverter TypeConverter { get; set; }
 
 		/// <summary>
 		/// Gets or sets the type converter options.
@@ -102,7 +102,7 @@ public virtual Type Type
 		/// <summary>
 		/// Gets or sets the default value used when a CSV field is empty.
 		/// </summary>
-		public virtual object? Default { get; set; }
+		public virtual object Default { get; set; }
 
 		/// <summary>
 		/// Gets or sets a value indicating whether this instance is default value set.
@@ -121,7 +121,7 @@ public virtual Type Type
 		/// <summary>
 		/// Gets or sets the constant value used for every record.
 		/// </summary>
-		public virtual object? Constant { get; set; }
+		public virtual object Constant { get; set; }
 
 		/// <summary>
 		/// Gets or sets a value indicating if a constant was explicitly set.
@@ -159,7 +159,7 @@ public virtual Type Type
 		/// Initializes a new instance of the <see cref="MemberMapData"/> class.
 		/// </summary>
 		/// <param name="member">The member.</param>
-		public MemberMapData(MemberInfo? member)
+		public MemberMapData(MemberInfo member)
 		{
 			Member = member;
 		}

src/CsvHelper/Configuration/MemberMap`1.cs

@@ -18,7 +18,7 @@ public class MemberMap<TClass, TMember> : MemberMap
 		/// <summary>
 		/// Creates a new <see cref="MemberMap"/> instance using the specified member.
 		/// </summary>
-		public MemberMap(MemberInfo? member)
+		public MemberMap(MemberInfo member)
 		{
 			TypeConverterOption = new MemberMapTypeConverterOption(this);
 
@@ -146,7 +146,7 @@ public virtual MemberMap<TClass, TMember> Default(string defaultValue, bool useO
 		/// what other mapping configurations are specified.
 		/// </summary>
 		/// <param name="constantValue">The constant value.</param>
-		public virtual MemberMap<TClass, TMember> Constant(TMember? constantValue)
+		public virtual MemberMap<TClass, TMember> Constant(TMember constantValue)
 		{
 			Data.Constant = constantValue;
 			Data.IsConstantSet = true;

src/CsvHelper/Configuration/MemberReferenceMap.cs

@@ -42,7 +42,7 @@ public MemberReferenceMap(MemberInfo member, ClassMap mapping)
 		/// <param name="prefix">The prefix to be prepended to headers of each reference member.</param>
 		/// <param name="inherit">Inherit parent prefixes.</param>
 		/// <returns>The current <see cref="MemberReferenceMap" /></returns>
-		public MemberReferenceMap Prefix(string? prefix = null, bool inherit = false)
+		public MemberReferenceMap Prefix(string prefix = null, bool inherit = false)
 		{
 			if (string.IsNullOrEmpty(prefix))
 			{

src/CsvHelper/Configuration/MemberReferenceMapCollection.cs

@@ -136,7 +136,7 @@ public virtual void RemoveAt(int index)
 		/// <typeparam name="T">The <see cref="System.Type"/> the member is on.</typeparam>
 		/// <param name="expression">The member expression.</param>
 		/// <returns>The <see cref="MemberReferenceMap"/> for the given expression, or null if not found.</returns>
-		public virtual MemberReferenceMap? Find<T>(Expression<Func<T, object>> expression)
+		public virtual MemberReferenceMap Find<T>(Expression<Func<T, object>> expression)
 		{
 			var member = ReflectionHelper.GetMember(expression);
 			return Find(member);
@@ -147,7 +147,7 @@ public virtual void RemoveAt(int index)
 		/// </summary>
 		/// <param name="member">The member.</param>
 		/// <returns>The <see cref="MemberReferenceMap"/> for the given expression, or null if not found.</returns>
-		public virtual MemberReferenceMap? Find(MemberInfo member)
+		public virtual MemberReferenceMap Find(MemberInfo member)
 		{
 			var existingMap = list.SingleOrDefault(m =>
 				m.Data.Member == member ||

src/CsvHelper/Configuration/ParameterMap.cs

@@ -127,7 +127,7 @@ public virtual ParameterMap Ignore(bool ignore)
 		/// the CSV field is empty.
 		/// </summary>
 		/// <param name="defaultValue">The default value.</param>
-		public virtual ParameterMap Default(object? defaultValue)
+		public virtual ParameterMap Default(object defaultValue)
 		{
 			if (defaultValue == null && Data.Parameter.ParameterType.IsValueType)
 			{
@@ -151,7 +151,7 @@ public virtual ParameterMap Default(object? defaultValue)
 		/// what other mapping configurations are specified.
 		/// </summary>
 		/// <param name="constantValue">The constant value.</param>
-		public virtual ParameterMap Constant(object? constantValue)
+		public virtual ParameterMap Constant(object constantValue)
 		{
 			if (constantValue == null && Data.Parameter.ParameterType.IsValueType)
 			{

src/CsvHelper/Configuration/ParameterMapData.cs

@@ -70,7 +70,7 @@ public class ParameterMapData
 		/// <summary>
 		/// Gets or sets the default value used when a CSV field is empty.
 		/// </summary>
-		public virtual object? Default { get; set; }
+		public virtual object Default { get; set; }
 
 		/// <summary>
 		/// Gets or sets a value indicating whether this instance is default value set.
@@ -82,7 +82,7 @@ public class ParameterMapData
 		/// <summary>
 		/// Gets or sets the constant value used for every record.
 		/// </summary>
-		public virtual object? Constant { get; set; }
+		public virtual object Constant { get; set; }
 
 		/// <summary>
 		/// Gets or sets a value indicating if a constant was explicitly set.

src/CsvHelper/CsvDataReader.cs

@@ -72,7 +72,7 @@ public int FieldCount
 		/// </summary>
 		/// <param name="csv">The CSV.</param>
 		/// <param name="schemaTable">The DataTable representing the file schema.</param>
-		public CsvDataReader(CsvReader csv, DataTable? schemaTable = null)
+		public CsvDataReader(CsvReader csv, DataTable schemaTable = null)
 		{
 			this.csv = csv;
 
@@ -116,7 +116,7 @@ public byte GetByte(int i)
 		}
 
 		/// <inheritdoc />
-		public long GetBytes(int i, long fieldOffset, byte[]? buffer, int bufferoffset, int length)
+		public long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length)
 		{
 			var bytes = csv.GetField<byte[]>(i);
 
@@ -134,7 +134,7 @@ public char GetChar(int i)
 		}
 
 		/// <inheritdoc />
-		public long GetChars(int i, long fieldoffset, char[]? buffer, int bufferoffset, int length)
+		public long GetChars(int i, long fieldoffset, char[] buffer, int bufferoffset, int length)
 		{
 			var chars = csv.GetField(i).ToCharArray();
 

src/CsvHelper/CsvParser.cs

@@ -74,7 +74,7 @@ public class CsvParser : IParser, IDisposable
 		private bool fieldIsQuoted;
 		private bool isProcessingField;
 		private bool isRecordProcessed;
-		private string[]? record;
+		private string[] record;
 
 		/// <inheritdoc/>
 		public long CharCount => charCount;
@@ -86,7 +86,7 @@ public class CsvParser : IParser, IDisposable
 		public int Row => row;
 
 		/// <inheritdoc/>
-		public string[]? Record
+		public string[] Record
 		{
 			get
 			{