subprojects/parseq/src/main/java/com/linkedin/parseq/promise/Promises.java
public static <T> void propagateResult(final Promise<T> source, final Settable<T> dest) {
    source.addListener(new TransformingPromiseListener<T, T>(dest, PromiseTransformer.identity()));
  }
public static <T> void propagateResult(final Promise<T> source, final Settable<T> dest) {
    source.addListener(new TransformingPromiseListener<T, T>(dest, PromiseTransformer.identity()));
  }
Copies the value or error from the source promise to the destination
promise.

@param source the source promise
@param dest the destination promise
@param <T> the value type for both promises