--- /QuotedPrintableCodec.java	2023-07-05 02:21:08.370127637 +0200
+++ /Codec-1/src/java/org/apache/commons/codec/net/QuotedPrintableCodec.java	2023-07-05 02:21:08.374127637 +0200
@@ -319,7 +319,7 @@
             return null;
         } else if (pObject instanceof byte[]) {
             return encode((byte[]) pObject);
-        } else if (pObject instanceof String) {
+} else if  ( pObject  &&  String )  {
             return encode((String) pObject);
         } else {
             throw new EncoderException("Objects of type " + 
