Create rule S6588: Use UnixEpoch instead of creating DateTime instances that point to the unix epoch time (#1747)

rules/S6588/csharp/metadata.json

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+{
+}

rules/S6588/csharp/rule.adoc

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+include::../why-dotnet.adoc[]
+
+include::../impact-dotnet.adoc[]
+
+include::../how-dotnet.adoc[]
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,csharp,diff-id=1,diff-type=noncompliant]
+----
+void GetEpochTime()
+{
+    var epochTime = new DateTime(1970, 1, 1);
+}
+----
+
+==== Compliant solution
+
+[source,csharp,diff-id=1,diff-type=compliant]
+----
+void GetEpochTime()
+{
+    var epochTime = DateTime.UnixEpoch;
+}
+----
+
+include::../resources-dotnet.adoc[]

rules/S6588/how-dotnet.adoc

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+== How to fix it
+
+To fix this issue, use the `UnixEpoch` field of `DateTime` or `DateTimeOffset` instead of the constructor.

rules/S6588/impact-dotnet.adoc

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+=== What is the potential impact?
+
+You should not use the `DateTime` or `DateTimeOffset` constructors to set the time to the 1st of January 1970 to represent the beginning of the Unix epoch. Not everyone is familiar with what this particular date is representing and it can be misleading.

rules/S6588/metadata.json

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+{
+  "title": "Use the \"UnixEpoch\" field instead of creating \"DateTime\" instances that point to the beginning of the Unix epoch",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+  ],
+  "extra": {
+  },
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-6588",
+  "sqKey": "S6588",
+  "scope": "All",
+  "defaultQualityProfiles": ["Sonar way"],
+  "quickfix": "targeted"
+}

rules/S6588/resources-dotnet.adoc

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+== Resources
+=== Documentation
+
+* https://learn.microsoft.com/en-us/dotnet/api/system.datetime.unixepoch[DateTime.UnixEpoch documentation]
+* https://learn.microsoft.com/en-us/dotnet/api/system.datetimeoffset.unixepoch[DateTimeOffset.UnixEpoch documentation]
+* https://en.wikipedia.org/wiki/Unix_time[Unix time]

rules/S6588/vbnet/metadata.json

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+{
+}

rules/S6588/vbnet/rule.adoc

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+include::../why-dotnet.adoc[]
+
+include::../impact-dotnet.adoc[]
+
+include::../how-dotnet.adoc[]
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,vbnet,diff-id=1,diff-type=noncompliant]
+----
+Private Sub GetEpochTime()
+    Dim epochTime = New DateTime(1970, 1, 1)
+End Sub
+----
+
+==== Compliant solution
+
+[source,vbnet,diff-id=1,diff-type=compliant]
+----
+Private Sub GetEpochTime()
+    Dim epochTime = DateTime.UnixEpoch
+End Sub
+----
+
+include::../resources-dotnet.adoc[]

rules/S6588/why-dotnet.adoc

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+== Why is this an issue?
+
+With .NET Core the `UnixEpoch` field was introduced to `DateTime` and `DateTimeOffset` types. Using this field clearly states that the intention is to use the beginning of the Unix epoch.