# System.Net.Http.Headers

``` diff
 namespace System.Net.Http.Headers {
     public class AuthenticationHeaderValue : ICloneable {
-        public static AuthenticationHeaderValue Parse(string? input);
+        public static AuthenticationHeaderValue Parse(string input);
     }
     public class CacheControlHeaderValue : ICloneable {
-        public static bool TryParse(string? input, out CacheControlHeaderValue? parsedValue);
+        public static bool TryParse(string? input, [NotNullWhenAttribute(true)] out CacheControlHeaderValue? parsedValue);
     }
     public class ContentDispositionHeaderValue : ICloneable {
-        public static ContentDispositionHeaderValue Parse(string? input);
+        public static ContentDispositionHeaderValue Parse(string input);
     }
     public class ContentRangeHeaderValue : ICloneable {
-        public static ContentRangeHeaderValue Parse(string? input);
+        public static ContentRangeHeaderValue Parse(string input);
     }
     public class EntityTagHeaderValue : ICloneable {
-        public static EntityTagHeaderValue Parse(string? input);
+        public static EntityTagHeaderValue Parse(string input);
     }
     public class MediaTypeHeaderValue : ICloneable {
-        public static MediaTypeHeaderValue Parse(string? input);
+        public static MediaTypeHeaderValue Parse(string input);
     }
     public sealed class MediaTypeWithQualityHeaderValue : MediaTypeHeaderValue, ICloneable {
-        public static new MediaTypeWithQualityHeaderValue Parse(string? input);
+        public static new MediaTypeWithQualityHeaderValue Parse(string input);
     }
     public class NameValueHeaderValue : ICloneable {
-        public static NameValueHeaderValue Parse(string? input);
+        public static NameValueHeaderValue Parse(string input);
     }
     public class NameValueWithParametersHeaderValue : NameValueHeaderValue, ICloneable {
-        public static new NameValueWithParametersHeaderValue Parse(string? input);
+        public static new NameValueWithParametersHeaderValue Parse(string input);
     }
     public class ProductHeaderValue : ICloneable {
-        public static ProductHeaderValue Parse(string? input);
+        public static ProductHeaderValue Parse(string input);
     }
     public class RangeConditionHeaderValue : ICloneable {
-        public static RangeConditionHeaderValue Parse(string? input);
+        public static RangeConditionHeaderValue Parse(string input);
     }
     public class RangeHeaderValue : ICloneable {
-        public static RangeHeaderValue Parse(string? input);
+        public static RangeHeaderValue Parse(string input);
     }
     public class RetryConditionHeaderValue : ICloneable {
-        public static RetryConditionHeaderValue Parse(string? input);
+        public static RetryConditionHeaderValue Parse(string input);
     }
     public class StringWithQualityHeaderValue : ICloneable {
-        public static StringWithQualityHeaderValue Parse(string? input);
+        public static StringWithQualityHeaderValue Parse(string input);
     }
     public class TransferCodingHeaderValue : ICloneable {
-        public static TransferCodingHeaderValue Parse(string? input);
+        public static TransferCodingHeaderValue Parse(string input);
     }
     public sealed class TransferCodingWithQualityHeaderValue : TransferCodingHeaderValue, ICloneable {
-        public static new TransferCodingWithQualityHeaderValue Parse(string? input);
+        public static new TransferCodingWithQualityHeaderValue Parse(string input);
     }
     public class ViaHeaderValue : ICloneable {
-        public static ViaHeaderValue Parse(string? input);
+        public static ViaHeaderValue Parse(string input);
     }
     public class WarningHeaderValue : ICloneable {
-        public static WarningHeaderValue Parse(string? input);
+        public static WarningHeaderValue Parse(string input);
     }
 }
```

