[dotnet] Annotate nullability for DriverService and chromium/safari services (SeleniumHQ#15101)

* [dotnet] Annotate nullability for `DriverService` and some derived types

* Default values to `null` instead of sentinel values.

Author: RenderMichael

dotnet/src/webdriver/Chromium/ChromiumDriverService.cs

@@ -21,6 +21,8 @@
 using System.Globalization;
 using System.Text;
 
+#nullable enable
+
 namespace OpenQA.Selenium.Chromium
 {
     /// <summary>
@@ -30,15 +32,6 @@ public abstract class ChromiumDriverService : DriverService
     {
         private const string DefaultChromeDriverServiceExecutableName = "chromedriver";
 
-        private string logPath = string.Empty;
-        private string urlPathPrefix = string.Empty;
-        private string portServerAddress = string.Empty;
-        private string allowedIPAddresses = string.Empty;
-        private int adbPort = -1;
-        private bool disableBuildCheck;
-        private bool enableVerboseLogging;
-        private bool enableAppendLog;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="ChromiumDriverService"/> class.
         /// </summary>
@@ -51,94 +44,64 @@ protected ChromiumDriverService(string executablePath, string executableFileName
         }
 
         /// <summary>
-        /// Gets or sets the location of the log file written to by the ChromeDriver executable.
+        /// <para>Gets or sets the location of the log file written to by the ChromeDriver executable.</para>
+        /// <para><see langword="null"/> or <see cref="string.Empty"/> signify no log path.</para>
         /// </summary>
-        public string LogPath
-        {
-            get { return this.logPath; }
-            set { this.logPath = value; }
-        }
+        public string? LogPath { get; set; }
 
         /// <summary>
-        /// Gets or sets the base URL path prefix for commands (e.g., "wd/url").
+        /// <para>Gets or sets the base URL path prefix for commands (e.g., "wd/url").</para>
+        /// <para><see langword="null"/> or <see cref="string.Empty"/> signify no prefix.</para>
         /// </summary>
-        public string UrlPathPrefix
-        {
-            get { return this.urlPathPrefix; }
-            set { this.urlPathPrefix = value; }
-        }
+        public string? UrlPathPrefix { get; set; }
 
         /// <summary>
-        /// Gets or sets the address of a server to contact for reserving a port.
+        /// <para>Gets or sets the address of a server to contact for reserving a port.</para>
+        /// <para><see langword="null"/> or <see cref="string.Empty"/> signify no port server.</para>
         /// </summary>
-        public string PortServerAddress
-        {
-            get { return this.portServerAddress; }
-            set { this.portServerAddress = value; }
-        }
+        public string? PortServerAddress { get; set; }
 
         /// <summary>
-        /// Gets or sets the port on which the Android Debug Bridge is listening for commands.
+        /// <para>Gets or sets the port on which the Android Debug Bridge is listening for commands.</para>
+        /// <para>A value less than or equal to 0, or <see langword="null"/>, indicates no Android Debug Bridge specified.</para>
         /// </summary>
-        public int AndroidDebugBridgePort
-        {
-            get { return this.adbPort; }
-            set { this.adbPort = value; }
-        }
+        public int? AndroidDebugBridgePort { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether to skip version compatibility check
         /// between the driver and the browser.
         /// Defaults to <see langword="false"/>.
         /// </summary>
-        public bool DisableBuildCheck
-        {
-            get { return this.disableBuildCheck; }
-            set { this.disableBuildCheck = value; }
-        }
+        public bool DisableBuildCheck { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether to enable verbose logging for the ChromeDriver executable.
         /// Defaults to <see langword="false"/>.
         /// </summary>
-        public bool EnableVerboseLogging
-        {
-            get { return this.enableVerboseLogging; }
-            set { this.enableVerboseLogging = value; }
-        }
+        public bool EnableVerboseLogging { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether to enable appending to an existing ChromeDriver log file.
         /// Defaults to <see langword="false"/>.
         /// </summary>
-        public bool EnableAppendLog
-        {
-            get { return this.enableAppendLog; }
-            set { this.enableAppendLog = value; }
-        }
+        public bool EnableAppendLog { get; set; }
 
         /// <summary>
-        /// Gets or sets the comma-delimited list of IP addresses that are approved to
-        /// connect to this instance of the Chrome driver. Defaults to an empty string,
-        /// which means only the local loopback address can connect.
+        /// <para>Gets or sets the comma-delimited list of IP addresses that are approved to connect to this instance of the Chrome driver.</para>
+        /// <para>A value of <see langword="null"/> or <see cref="string.Empty"/> means only the local loopback address can connect.</para>
         /// </summary>
         [Obsolete($"Use {nameof(AllowedIPAddresses)}")]
-        public string WhitelistedIPAddresses
+        public string? WhitelistedIPAddresses
         {
-            get { return this.allowedIPAddresses; }
-            set { this.allowedIPAddresses = value; }
+            get => this.AllowedIPAddresses;
+            set => this.AllowedIPAddresses = value;
         }
 
         /// <summary>
-        /// Gets or sets the comma-delimited list of IP addresses that are approved to
-        /// connect to this instance of the Chrome driver. Defaults to an empty string,
-        /// which means only the local loopback address can connect.
+        /// <para>Gets or sets the comma-delimited list of IP addresses that are approved to connect to this instance of the Chrome driver.</para>
+        /// <para>A value of <see langword="null"/> or <see cref="string.Empty"/> means only the local loopback address can connect.</para>
         /// </summary>
-        public string AllowedIPAddresses
-        {
-            get => this.allowedIPAddresses;
-            set => this.allowedIPAddresses = value;
-        }
+        public string? AllowedIPAddresses { get; set; }
 
         /// <summary>
         /// Gets the command-line arguments for the driver service.
@@ -148,49 +111,49 @@ protected override string CommandLineArguments
             get
             {
                 StringBuilder argsBuilder = new StringBuilder(base.CommandLineArguments);
-                if (this.adbPort > 0)
+                if (this.AndroidDebugBridgePort is int adb && adb > 0)
                 {
-                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --adb-port={0}", this.adbPort);
+                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --adb-port={0}", adb);
                 }
 
                 if (this.SuppressInitialDiagnosticInformation)
                 {
                     argsBuilder.Append(" --silent");
                 }
 
-                if (this.disableBuildCheck)
+                if (this.DisableBuildCheck)
                 {
                     argsBuilder.Append(" --disable-build-check");
                 }
 
-                if (this.enableVerboseLogging)
+                if (this.EnableVerboseLogging)
                 {
                     argsBuilder.Append(" --verbose");
                 }
 
-                if (this.enableAppendLog)
+                if (this.EnableAppendLog)
                 {
                     argsBuilder.Append(" --append-log");
                 }
 
-                if (!string.IsNullOrEmpty(this.logPath))
+                if (!string.IsNullOrEmpty(this.LogPath))
                 {
-                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --log-path=\"{0}\"", this.logPath);
+                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --log-path=\"{0}\"", this.LogPath);
                 }
 
-                if (!string.IsNullOrEmpty(this.urlPathPrefix))
+                if (!string.IsNullOrEmpty(this.UrlPathPrefix))
                 {
-                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --url-base={0}", this.urlPathPrefix);
+                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --url-base={0}", this.UrlPathPrefix);
                 }
 
-                if (!string.IsNullOrEmpty(this.portServerAddress))
+                if (!string.IsNullOrEmpty(this.PortServerAddress))
                 {
-                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --port-server={0}", this.portServerAddress);
+                    argsBuilder.AppendFormat(CultureInfo.InvariantCulture, " --port-server={0}", this.PortServerAddress);
                 }
 
-                if (!string.IsNullOrEmpty(this.allowedIPAddresses))
+                if (!string.IsNullOrEmpty(this.AllowedIPAddresses))
                 {
-                    argsBuilder.Append(string.Format(CultureInfo.InvariantCulture, " -allowed-ips={0}", this.allowedIPAddresses));
+                    argsBuilder.Append(string.Format(CultureInfo.InvariantCulture, " -allowed-ips={0}", this.AllowedIPAddresses));
                 }
 
                 return argsBuilder.ToString();