fix exception text

core/java/src/net/i2p/data/Hash.java

@@ -140,7 +140,7 @@ public class Hash extends DataStructureImpl {
     
     public void writeBytes(OutputStream out) throws DataFormatException, IOException {
         if (_data == null) throw new DataFormatException("No data in the hash to write out");
-        if (_data.length != HASH_LENGTH) throw new DataFormatException("Invalid size of data in the private key");
+        if (_data.length != HASH_LENGTH) throw new DataFormatException("Invalid size of data in the hash");
         out.write(_data);
     }