Use StartsWith instead Contains

Author: buyaa-n

src/libraries/System.Private.CoreLib/src/System/Reflection/NullabilityInfoContext.cs

@@ -388,7 +388,7 @@ private NullabilityInfo GetNullabilityInfo(MemberInfo memberInfo, Type type, ILi
                 {
                     Type t = Nullable.GetUnderlyingType(genericArguments[i]) ?? genericArguments[i];
 
-                    if (!t.IsValueType || t.Name.Contains(ValueTuple))
+                    if (!t.IsValueType || t.Name.StartsWith(ValueTuple))
                     {
                         offset++;
                     }

src/libraries/System.Runtime/tests/System/Reflection/NullabilityInfoContextTests.cs

@@ -865,6 +865,7 @@ public static IEnumerable<object[]> NestedGenericsReturnParameterData()
 
         [Theory]
         [MemberData(nameof(NestedGenericsReturnParameterData))]
+        [SkipOnMono("Nullability attributes trimmed on Mono")]
         public void NestedGenericsReturnParameterTest(string methodName, NullabilityState enumState, NullabilityState innerTupleState,
             NullabilityState intState, NullabilityState outerTupleState, NullabilityState stringState, NullabilityState objectState)
         {