title: JasperReport renders parameters as null
body: <p>I have been testing how JasperReport works and so on but I've got a problem when trying to send parameters, they are simply rendered as null (already checked that they aren't null).</p>
  
  <p>Here it is the code so far:</p>
  
  <pre><code>    JasperReport report = JasperCompileManager
              .compileReport("/home/alvaro93/entorno_luna/report1.jrxml");
  
      Map&lt;String, String&gt; parametros = new HashMap&lt;String, String&gt;();
      parametros.put("variable1", "Test");
      List&lt;Map&lt;String, ?&gt;&gt; list = new ArrayList&lt;Map&lt;String, ?&gt;&gt;();
      list.add(parametros);
  
      JRMapCollectionDataSource dataSource = new  JRMapCollectionDataSource(list);
      JasperPrint jasperPrint = JasperFillManager.fillReport(report, new HashMap(),dataSource);
  
      JRExporter exporter = new JRPdfExporter();
      exporter.setParameter(JRExporterParameter.JASPER_PRINT, jasperPrint);
      exporter.setParameter(JRExporterParameter.OUTPUT_FILE, new java.io.File("/home/alvaro93/entorno_luna/report1.pdf"));
      JasperViewer.viewReport(jasperPrint, false);
      exporter.exportReport();
  </code></pre>
  
  <p>Thanks in advance.</p>