Function exponential_histogram_gate 

pub(crate) fn exponential_histogram_gate(
    histogram: &ExponentialHistogram,
) -> Result<(), ExponentialHistogramRejection>

Whole-metric acceptance, decided once for the encoder and for the resource descriptor, which must not describe a resource whose data was rejected. Individual points can still fail exponential_histogram_value. Raw-delta storage currently supports sums and explicit histograms; exponential histograms still require cumulative input. Delta-to-cumulative conversion is out of scope.