Method itemIf

core/src/main/java/org/apache/calcite/rel/RelWriter.java:72–72

Adds an input to the explanation of the current node, if a condition holds.

(String term, @Nullable Object value, boolean condition)

   * holds.
   */
  default RelWriter itemIf(String term, @Nullable Object value, boolean condition) {
    return condition ? item(term, value) : this;
  }