Ensure that decodeB64 returns a String rather than Bytes.

[bigkevmcd]

Changes

This changes the return value of the decodeB64 overload to ensure that it returns a string.

Fixes #608

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Release Notes

Changes the output of decodeB64 to return a string, rather than bytes.

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-triggers-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/interceptors/cel/cel.go	91.4%	87.9%	-3.4

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-triggers-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/interceptors/cel/cel.go	91.4%	87.9%	-3.4

[dibyom]

/kind bug
/approve

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[dibyom]

/lgtm

[bigkevmcd]

I should probably have explained why it was originally types.Bytes and not types.String, as it probably looks like a stupid bug :-)

When it's a string, it gets quoted when it's being inserted as an overlay value, what that means, is that previously, if you were decoding a base64 encoded JSON blob, the value that was inserted as, was a string, and not an object, so you couldn't use the fields.

Essentially, if you had something like {"value": "test"} encoded as base64, and you decoded it into an overlay as a types.String it would have looked like "overlay": "{\"value\": \"test\"}"} and then, if you tried to get body.overlay.value in a binding, you couldn't.

But, with the addition of parseJSON, this isn't so much of a problem, as you can decode the base64 and then parse the JSON.

body.value.decodeb64().parseJSON()