Output of list with empty string is the same to empty list

[dzavalkinolx]

Entrypoint in the image is []. If I create the following metadata test:

metadataTest:
  entrypoint: [""]

it will fail with error message:

    --- FAIL: TestAll/Metadata_Test (0.00s)
        structure.go:179: Image entrypoint [] does not match expected entrypoint: []

[datwiz]

This should get get addressed as part of the extension of the metadataTest for #80