code: @Override
      public Entry postEntry(final AtomRequest areq, final Entry entry) throws AtomException {
          LOG.debug("postEntry");
  
          final String[] pathInfo = StringUtils.split(areq.getPathInfo(), "/");
          final String handle = pathInfo[0];
          final String collection = pathInfo[1];
          final FileBasedCollection col = service.findCollectionByHandle(handle, collection);
          try {
              return col.addEntry(entry);
  
          } catch (final Exception fe) {
              fe.printStackTrace();
              throw new AtomException(fe);
          }
      }
docs: Create a new entry specified by pathInfo and posted entry. We save the submitted Atom entry
  verbatim, but we do set the id and reset the update time.
  
  @param entry Entry to be added to collection.
  @param areq Details of HTTP request
  @throws com.rometools.rome.propono.atom.server.AtomException On invalid collection or other
  error.
  @return Entry as represented on server.