1 files changed, 26 insertions, 40 deletions
diff --git a/crypto/src/asn1/ess/ContentIdentifier.cs b/crypto/src/asn1/ess/ContentIdentifier.cs
index 430185e11..0520653f3 100644
--- a/crypto/src/asn1/ess/ContentIdentifier.cs
+++ b/crypto/src/asn1/ess/ContentIdentifier.cs
@@ -1,54 +1,43 @@
 using System;
 
-using Org.BouncyCastle.Utilities;
-
 namespace Org.BouncyCastle.Asn1.Ess
 {
-	public class ContentIdentifier
+    public class ContentIdentifier
 		: Asn1Encodable
 	{
-		private Asn1OctetString value;
-
-		public static ContentIdentifier GetInstance(
-			object o)
-		{
-			if (o == null || o is ContentIdentifier)
-			{
-				return (ContentIdentifier) o;
-			}
-
-			if (o is Asn1OctetString)
-			{
-				return new ContentIdentifier((Asn1OctetString) o);
-			}
-
-			throw new ArgumentException(
-				"unknown object in 'ContentIdentifier' factory : "
-                + Platform.GetTypeName(o) + ".");
-		}
-
-		/**
+        public static ContentIdentifier GetInstance(object o)
+        {
+            if (o == null)
+                return null;
+            if (o is ContentIdentifier contentIdentifier)
+                return contentIdentifier;
+            return new ContentIdentifier(Asn1OctetString.GetInstance(o));
+        }
+
+        public static ContentIdentifier GetInstance(Asn1TaggedObject taggedObject, bool declaredExplicit)
+        {
+            return new ContentIdentifier(Asn1OctetString.GetInstance(taggedObject, declaredExplicit));
+        }
+
+        private readonly Asn1OctetString m_value;
+
+        /**
 		 * Create from OCTET STRING whose octets represent the identifier.
 		 */
-		public ContentIdentifier(
-			Asn1OctetString value)
-		{
-			this.value = value;
-		}
+        public ContentIdentifier(Asn1OctetString value)
+        {
+            m_value = value ?? throw new ArgumentNullException(nameof(value));
+        }
 
-		/**
+        /**
 		 * Create from byte array representing the identifier.
 		 */
-		public ContentIdentifier(
-			byte[] value)
+        public ContentIdentifier(byte[] value)
 			: this(new DerOctetString(value))
 		{
 		}
 
-		public Asn1OctetString Value
-		{
-			get { return value; }
-		}
+		public Asn1OctetString Value => m_value;
 
 		/**
 		 * The definition of ContentIdentifier is
@@ -59,9 +48,6 @@ namespace Org.BouncyCastle.Asn1.Ess
 		 *  member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
 		 *  smime(16) id-aa(2) 7 }
 		 */
-		public override Asn1Object ToAsn1Object()
-		{
-			return value;
-		}
+		public override Asn1Object ToAsn1Object() => m_value;
 	}
 }