openrtb-core/src/main/java/com/google/openrtb/util/OpenRtbUtils.java
@Nullable public static Imp impWithId(BidRequest request, String id) {
    checkNotNull(id);

    for (Imp imp : request.getImpList()) {
      if (imp.getId().equals(id)) {
        return imp;
      }
    }

    return null;
  }
@Nullable public static Imp impWithId(BidRequest request, String id) {
    checkNotNull(id);

    for (Imp imp : request.getImpList()) {
      if (imp.getId().equals(id)) {
        return imp;
      }
    }

    return null;
  }
Finds an {@link Imp} by ID.

@return The {@link Imp}s that has the given id, or {@code null} if not found.