Currently thresholdRules with a threshold of "0" are not valid.

Example:

assessContainerImage(
        failOnPluginError: true,
        imageId: "${IMAGE}",
        thresholdRules: [
                exploitableVulnerabilities(threshold: '0', action: 'Fail'),
        ]
)

From the logs:

WARN: Skipping invalid rule: Exploitable vulnerability count exceeds 0

Expectation:
A value of zero should be valid, as the plugin should be able mark the build as failed if at least one (that means greater than zero)  thresholdRule with an exceeded threshold is found.