code: public void addParameter(String name, String value) {
  
          // No null values allowed in parameters
          if ((name == null) || (value == null)) {
              return;
          }
  
          // Check if internal map exists, create new one if not
          if (m_parameterMap == null) {
              m_parameterMap = new HashMap<String, String[]>();
          }
  
          addParameter(m_parameterMap, name, value, false);
      }
docs: This methods adds parameters to the current request.<p>
  
  Parameters added here will be treated like parameters from the
  HttpRequest on included pages.<p>
  
  Remember that the value for a parameter in a HttpRequest is a
  String array, not just a simple String. If a parameter added here does
  not already exist in the HttpRequest, it will be added. If a parameter
  exists, another value will be added to the array of values. If the
  value already exists for the parameter, nothing will be added, since a
  value can appear only once per parameter.<p>
  
  @param name the name to add
  @param value the value to add
  @see org.opencms.jsp.I_CmsJspTagParamParent#addParameter(String, String)