OSM XML Polygon from relation example

multipolygon.geojson

{
  "type": "Feature",
  "geometry": {
    "type": "Polygon",
    "coordinates": [
      [
        [-75.22935060778029, -0.5708135940038386],
        [-75.22912591409263, -0.5705752943384652],
        [-75.22970467056082, -0.569874012408833],
        [-75.22992255534885, -0.5701055035406826],
        [-75.22935060778029, -0.5708135940038386]
      ]
    ]
  },
  "properties": {
    "type": "waterway",
    "waterway": "river",
    "name": "Rio Lagarto"
  }
}

multipolygon.xml

<osm generator="obj2osm" version="0.6">
  <node lon="-75.22970467056082" lat="-0.569874012408833" changeset="10342675312569811216" id="11843578656902644212" version="1ba46d691225abbf0c55db07e7e21c594330e116d2086ff83f8e5aeafbfbab6d"/>
  <node lon="-75.22992255534885" lat="-0.5701055035406826" changeset="10342675312569811216" id="10539940156884797648" version="3fb20b881c47c0b7bb7a22f3fb52d8138f5b1fb99f56b171b892db20c83b9644"/>
  <node lon="-75.2294050789773" lat="-0.5702144405406864" changeset="10342675312569811216" id="8071506864511733271" version="7c8c4fdcada9a954eb2ece2718af4e450f6a7a7207b5baa3e8461397950bd046"/>
  <node lon="-75.22964339046419" lat="-0.5704323145345112" changeset="10342675312569811216" id="16728392732403395704" version="bd6a725291c3036b65f7c307c53b52773ef57238a36ed626d62012260f76cfa4"/>
  <node lon="-75.22912591409263" lat="-0.5705752943384652" changeset="10342675312569811216" id="9791969132495086782" version="902547f09ba63954c4c8b14d707df4702e87ae62c8e007d36d6c5cc4ec07854e"/>
  <node lon="-75.22935060778029" lat="-0.5708135940038386" changeset="10342675312569811216" id="16839155776375139683" version="92c8e99a73cf93860b4faa6a809c1d7d01f774f99e71e5132852420c375e14c2"/>
  <way changeset="10342675312569811216" id="12715558374348913557" version="27a7d4301626293eb49ee41f8fd29523bfa0490f9949d78ebcaa78f7d08c8b06">
    <nd ref="10539940156884797648"/>
    <nd ref="11843578656902644212"/>
    <nd ref="8071506864511733271"/>
    <nd ref="16728392732403395704"/>
    <nd ref="10539940156884797648"/>
    <tag k="natural" v="water"/>
    <tag k="water" v="river"/>
    <tag k="area" v="yes"/>
  </way>
  <way changeset="10342675312569811216" id="12319058023184236721" version="c6115cf9cb4b686d7c03f578d495123a4870b839c146b266f34e1190fe96d96e">
    <nd ref="8071506864511733271"/>
    <nd ref="16728392732403395704"/>
    <nd ref="16839155776375139683"/>
    <nd ref="9791969132495086782"/>
    <nd ref="8071506864511733271"/>
    <tag k="natural" v="water"/>
    <tag k="water" v="river"/>
    <tag k="area" v="yes"/>
  </way>
  <relation changeset="10342675312569811216" id="9442459380136829045" version="d075ecde1cc0f0cad2a8200302e049f5f8cb44db6cbf26eb6c20de638b6a1c1c">
    <member ref="12715558374348913557" role="" type="way"/>
    <member ref="12319058023184236721" role="" type="way"/>
    <tag k="type" v="waterway"/>
    <tag k="waterway" v="river"/>
    <tag k="name" v="Rio Lagarto"/>
  </relation>
</osm>