SignatureHelp and CompletionItem spec fix

src/Protocol/Models/CompletionItem.cs

@@ -27,6 +27,7 @@ public class CompletionItem : ICanBeResolved, IRequest<CompletionItem>
         ///
         /// @since 3.15.0
         /// </summary>
+        [Optional]
         public Container<CompletionItemTag> Tags { get; set; }
 
         /// <summary>

src/Protocol/Models/SignatureHelp.cs

@@ -12,7 +12,7 @@ public class SignatureHelp
         /// <summary>
         /// One or more signatures.
         /// </summary>
-        public Container<SignatureInformation> Signatures { get; set; }
+        public Container<SignatureInformation> Signatures { get; set; } = new Container<SignatureInformation>();
 
         /// <summary>
         /// The active signature.

test/Lsp.Tests/Models/CompletionItemTests_$SimpleTest.json

@@ -1,7 +1,6 @@
 {
     "label": null,
     "kind": 1,
-    "tags": null,
     "deprecated": false,
     "preselect": false,
     "insertTextFormat": 0,

test/Lsp.Tests/Models/CompletionListTests_$ComplexTest.json

@@ -4,7 +4,6 @@
         {
             "label": null,
             "kind": 7,
-            "tags": null,
             "detail": "details",
             "deprecated": false,
             "preselect": false,

test/Lsp.Tests/Models/CompletionListTests_$SimpleTest.json

@@ -2,7 +2,6 @@
     {
         "label": null,
         "kind": 7,
-        "tags": null,
         "detail": "details",
         "deprecated": false,
         "preselect": false,

test/Lsp.Tests/Models/SignatureHelpTests.cs

@@ -31,5 +31,17 @@ public void SimpleTest(string expected)
             var deresult = new Serializer(ClientVersion.Lsp3).DeserializeObject<SignatureHelp>(expected);
             deresult.Should().BeEquivalentTo(model);
         }
+
+        [Theory, JsonFixture]
+        public void NoSignaturesTest(string expected)
+        {
+            var model = new SignatureHelp();
+            var result = Fixture.SerializeObject(model);
+
+            result.Should().Be(expected);
+
+            var deresult = new Serializer(ClientVersion.Lsp3).DeserializeObject<SignatureHelp>(expected);
+            deresult.Should().BeEquivalentTo(model);
+        }
     }
 }

test/Lsp.Tests/Models/SignatureHelpTests_$NoSignaturesTest.json

@@ -0,0 +1,3 @@
+{
+    "signatures": []
+}