[fix] adding key perfix for GetChildKeys

Author: i4004

README.md

@@ -58,7 +58,7 @@ appsettings.json
 var jsonConfig = new ConfigurationBuilder()
 	.AddJsonFile("appsettings.json")
 	.Build();
-	
+
 	var config = new ConfigurationBuilder()
 	.AddEtcd(
 		new Credentials("MyEtcdUserName", "passw"),

src/Etcd.Microsoft.Extensions.Configuration/EtcdConfigurationProvider.cs

@@ -48,6 +48,12 @@ public EtcdConfigurationProvider(IEtcdKeyValueClient client, string? keyPrefix =
 		/// </returns>
 		public override bool TryGet(string key, out string value) => base.TryGet(_keyPrefix + key, out value);
 
+		/// <summary>Returns the list of keys that this provider has.</summary>
+		/// <param name="earlierKeys">The earlier keys that other providers contain.</param>
+		/// <param name="parentPath">The path for the parent IConfiguration.</param>
+		/// <returns>The list of keys for this provider.</returns>
+		public override IEnumerable<string> GetChildKeys(IEnumerable<string> earlierKeys, string parentPath) => base.GetChildKeys(earlierKeys, _keyPrefix + parentPath);
+
 		/// <summary>
 		/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
 		/// </summary>