code: @Override
      public List<ProposalPersonContract> getCoInvestigators(ProposalDevelopmentDocumentContract pdDoc) {
          List<ProposalPersonContract> investigators = new ArrayList<>();
          if (pdDoc != null) {
              for (ProposalPersonContract person : pdDoc.getDevelopmentProposal().getProposalPersons()) {
                  //multi-pis are still considered co-i within S2S.
                  if (person.isCoInvestigator() || person.isMultiplePi()) {
                      investigators.add(person);
                  }
              }
          }
          return investigators;
      }
docs: Finds all the Investigators associated with the provided pdDoc.