code: public static void setFieldValue(final Field field, final Object instance, final Object value) throws CoreException {
  
          try {
              // store current visibility
              final boolean accessible = field.isAccessible();
  
              // let it accessible anyway
              field.setAccessible(true);
  
              // Call this method with right parameters
              field.set(instance, value);
  
              // Reset default visibility
              field.setAccessible(accessible);
  
          } catch (IllegalAccessException | IllegalArgumentException e) {
              throw new CoreException(e);
          }
      }
docs: Update an object field even if it has a private or protected visibility.
  
  @param field the field to update
  @param instance the object instance that hold this field
  @param value the value to set into this field
  
  @throws CoreException if the new value cannot be set