GitTools#3334 - fix nullable warnings

Author: arturcic

src/GitVersion.Core/Core/MergeCommitFinder.cs

@@ -24,10 +24,10 @@ public IEnumerable<BranchCommit> FindMergeCommitsFor(IBranch branch)
     {
         branch = branch.NotNull();
 
-        if (this.mergeBaseCommitsCache.ContainsKey(branch))
+        if (this.mergeBaseCommitsCache.TryGetValue(branch, out var mergeCommitsFor))
         {
-            this.log.Debug($"Cache hit for getting merge commits for branch {branch?.Name.Canonical}.");
-            return this.mergeBaseCommitsCache[branch];
+            this.log.Debug($"Cache hit for getting merge commits for branch {branch.Name.Canonical}.");
+            return mergeCommitsFor;
         }
 
         var branchMergeBases = FindMergeBases(branch)

src/GitVersion.Core/Extensions/DictionaryExtensions.cs

@@ -6,7 +6,8 @@ public static TValue GetOrAdd<TKey, TValue>(this IDictionary<TKey, TValue> dict,
     {
         if (dict is null) throw new ArgumentNullException(nameof(dict));
         if (getValue is null) throw new ArgumentNullException(nameof(getValue));
-        if (!dict.TryGetValue(key, out TValue value))
+
+        if (!dict.TryGetValue(key, out var value))
         {
             value = getValue();
             dict.Add(key, value);

src/GitVersion.Core/Extensions/ObjectExtensions.cs

@@ -16,11 +16,11 @@ public static void Deconstruct<TKey, TValue>(
         value = kvp.Value;
     }
 
-    public static IEnumerable<KeyValuePair<string, string>> GetProperties(this object obj)
+    public static Dictionary<string, string> GetProperties(this object obj)
     {
         var type = typeof(string);
         return obj.GetType().GetProperties()
             .Where(p => p.PropertyType == type && !p.GetIndexParameters().Any() && !p.GetCustomAttributes(typeof(ReflectionIgnoreAttribute), false).Any())
-            .Select(p => new KeyValuePair<string, string>(p.Name, (string)p.GetValue(obj, null)));
+            .ToDictionary(p => p.Name, p => Convert.ToString(p.GetValue(obj, null))!);
     }
 }