8261938: ASN1Formatter.annotate should not return in the finally block

Reviewed-by: rriggs

test/lib/jdk/test/lib/hexdump/ASN1Formatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -110,15 +110,24 @@ private ASN1Formatter() {
      * A single well formed tagged-value is read and annotated.
      *
      * @param in  a DataInputStream
-     * @throws IOException if an I/O error occurs
      */
-    public String annotate(DataInputStream in) throws IOException {
+    public String annotate(DataInputStream in) {
         StringBuilder sb = new StringBuilder();
         try {
             this.annotate(in, sb);
-        } finally {
-            return sb.toString();
+        } catch (IOException e) {
+            /*
+             * Formatters are designed to be nested, where one formatter can call another and the valuable output
+             * is the formatted string that has been accumulated from the beginning of the stream.
+             *
+             * The choice of DataInputStream was chosen for the convenience of the methods to read different types.
+             * and (declared) exceptions are an unwelcome artifact.
+             *
+             * If an exception was percolated up and the formatted output discarded, it would defeat the purpose.
+             * So we just catch it here and still return useful information about the stream to this point.
+             */
         }
+        return sb.toString();
     }
 
     /**