code: protected String getSignatureHash(Map<String, String> parameters) {
          List<String> values = new ArrayList<String>();
  
          StringBuilder data = new StringBuilder();
          data.append(this.apiSecret);
  
          for (Entry<String, String> entry : parameters.entrySet()) {
             values.add(entry.getValue());
          }
  
          Collections.sort(values);
  
          for( String value:values ) {
              data.append(value);
          }
          return SailthruUtil.md5(data.toString());
      }
docs: Get Signature Hash from given Map