code: public /*@Nullable*/DbxEntry copyFromCopyRef(String copyRef, String toPath)
          throws DbxException
      {
          if (copyRef == null) throw new IllegalArgumentException("'copyRef' can't be null");
          if (copyRef.length() == 0) throw new IllegalArgumentException("'copyRef' can't be empty");
          DbxPathV1.checkArgNonRoot("toPath", toPath);
  
          String[] params = {
              "root", "auto",
              "from_copy_ref", copyRef,
              "to_path", toPath,
          };
  
          return doPost(host.getApi(), "1/fileops/copy", params, null, new DbxRequestUtil.ResponseHandler</*@Nullable*/DbxEntry>()
          {
              @Override
              public /*@Nullable*/DbxEntry handle(HttpRequestor.Response response)
                  throws DbxException
              {
                  if (response.getStatusCode() != 200) throw DbxRequestUtil.unexpectedStatus(response);
                  DbxEntry.WithChildren dwc = DbxRequestUtil.readJsonFromResponse(DbxEntry.WithChildren.Reader, response);
                  if (dwc == null) return null;  // TODO: When can this happen?
                  return dwc.entry;
              }
          });
      }
docs: Create a file or folder at {@code toPath} based on the given copy ref (created with
  {@link #createCopyRef}).