rulebook-core/src/main/java/com/deliveredtechnologies/rulebook/StandardRule.java
@Override
  @SuppressWarnings("unchecked")
  public Rule<T> then(Consumer<FactMap<T>> action) {
    _actionChain.add(action);
    return this;
  }
@Override
  @SuppressWarnings("unchecked")
  public Rule<T> then(Consumer<FactMap<T>> action) {
    _actionChain.add(action);
    return this;
  }
The then() method accepts a {@link Consumer} that performs an action based on Facts.

@param action  the action to be performed
@return        the current object