Confusing comment in the code regarding getGDALMetadata

It is saying here:

If sample is passed to null, dataset-level metadata will be returned.

The question is what dataset-level metadata is? As I can see it simply returns metadata of the last band:

> img.fileDirectory.GDAL_METADATA;
'<GDALMetadata>\n' +
  '  <Item name="STATISTICS_MAXIMUM" sample="0">255</Item>\n' +
  '  <Item name="STATISTICS_MEAN" sample="0">161.13451304075</Item>\n' +
  '  <Item name="STATISTICS_MINIMUM" sample="0">27</Item>\n' +
  '  <Item name="STATISTICS_STDDEV" sample="0">47.78883943453</Item>\n' +
  '  <Item name="STATISTICS_VALID_PERCENT" sample="0">98.67</Item>\n' +
  '  <Item name="STATISTICS_MAXIMUM" sample="1">255</Item>\n' +
  '  <Item name="STATISTICS_MEAN" sample="1">156.19044508527</Item>\n' +
  '  <Item name="STATISTICS_MINIMUM" sample="1">17</Item>\n' +
  '  <Item name="STATISTICS_STDDEV" sample="1">45.653592048342</Item>\n' +
  '  <Item name="STATISTICS_VALID_PERCENT" sample="1">98.67</Item>\n' +
  '  <Item name="STATISTICS_MAXIMUM" sample="2">255</Item>\n' +
  '  <Item name="STATISTICS_MEAN" sample="2">156.71097900011</Item>\n' +
  '  <Item name="STATISTICS_MINIMUM" sample="2">1</Item>\n' +
  '  <Item name="STATISTICS_STDDEV" sample="2">41.777101570921</Item>\n' +
  '  <Item name="STATISTICS_VALID_PERCENT" sample="2">98.67</Item>\n' +
  '</GDALMetadata>\n' +
  '\x00'
> JSON.stringify(img.getGDALMetadata(0)) == JSON.stringify(img.getGDALMetadata())
false
> JSON.stringify(img.getGDALMetadata(1)) == JSON.stringify(img.getGDALMetadata())
false
> JSON.stringify(img.getGDALMetadata(2)) == JSON.stringify(img.getGDALMetadata())
true

cc @rouault

[DanielJDufour]

I’m on it

[constantinius]

Sorry, have missed this. I think it is most useful for getGDALMetadata() with no argument to only return global metadata, not any band specific metadata. Feel free to draft a PR @DanielJDufour