code: public Object readValue(final Attribute _attribute,
                              final List<Object> _objectList)
      {
          Object ret = null;
          if (_objectList.size() < 1) {
              ret = null;
          } else if (_objectList.size() > 1) {
              final List<Object> list = new ArrayList<Object>();
              for (final Object object : _objectList) {
                  Object obj = Boolean.FALSE;
                  if (object instanceof Boolean) {
                      obj = object;
                  } else if (object instanceof Number) {
                      final Integer intvalue = ((Number) object).intValue();
                      if ((intvalue != null) && (intvalue != 0)) {
                          obj = Boolean.TRUE;
                      } else {
                          obj = Boolean.FALSE;
                      }
                  }
                  list.add(obj);
              }
              ret = list;
          } else {
              final Object object = _objectList.get(0);
              if (object instanceof Boolean) {
                  ret = object;
              } else if (object instanceof Number) {
                  final Integer intvalue = ((Number) object).intValue();
                  if ((intvalue != null) && (intvalue != 0)) {
                      ret = Boolean.TRUE;
                  } else {
                      ret = Boolean.FALSE;
                  }
              }
          }
          return ret;
      }
docs: Evaluates the <code>_objectList</code> and interprets this value as
  boolean.
  
  @param _attribute        related eFaps attribute definition; not used
  @param _objectList       list of values for the attribute definition
  @return related interpreted boolean value if object list is
  {@link Boolean} or {@link Number}; otherwise <code>null</code>
  is returned