NIFI-8616 - Updated DelimitedInputStream to extend the FilterInputStream class. (#5203)

diff --git a/nifi-nar-bundles/nifi-extension-utils/nifi-event-transport/src/main/java/org/apache/nifi/event/transport/netty/DelimitedInputStream.java b/nifi-nar-bundles/nifi-extension-utils/nifi-event-transport/src/main/java/org/apache/nifi/event/transport/netty/DelimitedInputStream.java
index 4f6a4b1..bc1e81e 100644
--- a/nifi-nar-bundles/nifi-extension-utils/nifi-event-transport/src/main/java/org/apache/nifi/event/transport/netty/DelimitedInputStream.java
+++ b/nifi-nar-bundles/nifi-extension-utils/nifi-event-transport/src/main/java/org/apache/nifi/event/transport/netty/DelimitedInputStream.java
@@ -16,28 +16,22 @@
  */
 package org.apache.nifi.event.transport.netty;
 
-import java.io.IOException;
+import java.io.FilterInputStream;
 import java.io.InputStream;
 
 /**
  * A delimited InputStream which retains a delimiter for later use
  */
-public class DelimitedInputStream extends InputStream {
+public class DelimitedInputStream extends FilterInputStream {
 
-    private final InputStream in;
     private final byte[] delimiter;
 
     public DelimitedInputStream(final InputStream in, final byte[] delimiter) {
-        this.in = in;
+        super(in);
         this.delimiter = delimiter;
     }
 
     public byte[] getDelimiter() {
         return delimiter;
     }
-
-    @Override
-    public int read() throws IOException {
-        return in.read();
-    }
 }