code: private static Field getField(String fieldName, Class<?> where) {
          if (where == null) {
              throw new IllegalArgumentException("where cannot be null");
          }
  
          Field field = null;
          try {
              field = where.getDeclaredField(fieldName);
              field.setAccessible(true);
          } catch (NoSuchFieldException e) {
              throw new FieldNotFoundException("Field '" + fieldName + "' was not found in class " + where.getName()
                                                       + ".");
          }
          return field;
      }
docs: Gets the field.
  
  @param fieldName the field name
  @param where     the where
  @return the field