diff --git a/Pilz/NullableAttributes.cs b/Pilz/NullableAttributes.cs
new file mode 100644
index 0000000..036bc70
--- /dev/null
+++ b/Pilz/NullableAttributes.cs
@@ -0,0 +1,204 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if NETSTANDARD2_0
+
+namespace System.Diagnostics.CodeAnalysis;
+
+#if !NETSTANDARD2_1
+/// Specifies that null is allowed as an input even if the corresponding type disallows it.
+[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class AllowNullAttribute : Attribute
+{ }
+
+/// Specifies that null is disallowed as an input even if the corresponding type allows it.
+[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class DisallowNullAttribute : Attribute
+{ }
+
+/// Specifies that an output may be null even if the corresponding type disallows it.
+[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class MaybeNullAttribute : Attribute
+{ }
+
+/// Specifies that an output will not be null even if the corresponding type allows it. Specifies that an input argument was not null when the call returns.
+[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class NotNullAttribute : Attribute
+{ }
+
+/// Specifies that when a method returns , the parameter may be null even if the corresponding type disallows it.
+[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class MaybeNullWhenAttribute : Attribute
+{
+ /// Initializes the attribute with the specified return value condition.
+ ///
+ /// The return value condition. If the method returns this value, the associated parameter may be null.
+ ///
+ public MaybeNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;
+
+ /// Gets the return value condition.
+ public bool ReturnValue { get; }
+}
+
+/// Specifies that when a method returns , the parameter will not be null even if the corresponding type allows it.
+[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class NotNullWhenAttribute : Attribute
+{
+ /// Initializes the attribute with the specified return value condition.
+ ///
+ /// The return value condition. If the method returns this value, the associated parameter will not be null.
+ ///
+ public NotNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;
+
+ /// Gets the return value condition.
+ public bool ReturnValue { get; }
+}
+
+/// Specifies that the output will be non-null if the named parameter is non-null.
+[AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, AllowMultiple = true, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class NotNullIfNotNullAttribute : Attribute
+{
+ /// Initializes the attribute with the associated parameter name.
+ ///
+ /// The associated parameter name. The output will be non-null if the argument to the parameter specified is non-null.
+ ///
+ public NotNullIfNotNullAttribute(string parameterName) => ParameterName = parameterName;
+
+ /// Gets the associated parameter name.
+ public string ParameterName { get; }
+}
+
+/// Applied to a method that will never return under any circumstance.
+[AttributeUsage(AttributeTargets.Method, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class DoesNotReturnAttribute : Attribute
+{ }
+
+/// Specifies that the method will not return if the associated Boolean parameter is passed the specified value.
+[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class DoesNotReturnIfAttribute : Attribute
+{
+ /// Initializes the attribute with the specified parameter value.
+ ///
+ /// The condition parameter value. Code after the method will be considered unreachable by diagnostics if the argument to
+ /// the associated parameter matches this value.
+ ///
+ public DoesNotReturnIfAttribute(bool parameterValue) => ParameterValue = parameterValue;
+
+ /// Gets the condition parameter value.
+ public bool ParameterValue { get; }
+}
+#endif
+
+/// Specifies that the method or property will ensure that the listed field and property members have not-null values.
+[AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class MemberNotNullAttribute : Attribute
+{
+ /// Initializes the attribute with a field or property member.
+ ///
+ /// The field or property member that is promised to be not-null.
+ ///
+ public MemberNotNullAttribute(string member) => Members = [member];
+
+ /// Initializes the attribute with the list of field and property members.
+ ///
+ /// The list of field and property members that are promised to be not-null.
+ ///
+ public MemberNotNullAttribute(params string[] members) => Members = members;
+
+ /// Gets field or property member names.
+ public string[] Members { get; }
+}
+
+/// Specifies that the method or property will ensure that the listed field and property members have not-null values when returning with the specified return value condition.
+[AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if SYSTEM_PRIVATE_CORELIB
+public
+#else
+internal
+#endif
+ sealed class MemberNotNullWhenAttribute : Attribute
+{
+ /// Initializes the attribute with the specified return value condition and a field or property member.
+ ///
+ /// The return value condition. If the method returns this value, the associated field or property member will not be null.
+ ///
+ ///
+ /// The field or property member that is promised to be not-null.
+ ///
+ public MemberNotNullWhenAttribute(bool returnValue, string member)
+ {
+ ReturnValue = returnValue;
+ Members = [member];
+ }
+
+ /// Initializes the attribute with the specified return value condition and list of field and property members.
+ ///
+ /// The return value condition. If the method returns this value, the associated field and property members will not be null.
+ ///
+ ///
+ /// The list of field and property members that are promised to be not-null.
+ ///
+ public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
+ {
+ ReturnValue = returnValue;
+ Members = members;
+ }
+
+ /// Gets the return value condition.
+ public bool ReturnValue { get; }
+
+ /// Gets field or property member names.
+ public string[] Members { get; }
+}
+
+#endif
\ No newline at end of file
diff --git a/Pilz/Pilz.csproj b/Pilz/Pilz.csproj
index 3ae75c5..7fd3e61 100644
--- a/Pilz/Pilz.csproj
+++ b/Pilz/Pilz.csproj
@@ -1,11 +1,15 @@
- net8.0
+ net8.0;netstandard2.0
latest
enable
annotations
- 2.4.6
+ 2.4.7
+
+
+
+ $(NoWarn);nullable