@Override public void addMapping(final PropertyMapping mapping, final Object entry, final Field field) { if (field.getName().equals("substitutions")) { Set<EmployeeDO> substitutions = (Set<EmployeeDO>) BeanHelper.getFieldValue(entry, field); StringBuilder sb = new StringBuilder(); for (EmployeeDO sub : substitutions) { sb.append(", "); sb.append(sub.getUser().getFullname()); } if (sb.length() > 2) { mapping.add(field.getName(), sb.substring(2)); } else { mapping.add(field.getName(), ""); } } else { super.addMapping(mapping, entry, field); } } };