public SummaryField getExplicitSummaryField(String name) {
        for (DocumentSummary summary : summaries.values()) {
            SummaryField summaryField = summary.getSummaryField(name);
            if (summaryField != null && !summaryField.isImplicit())
                return summaryField;
        }
        if (inherited.isEmpty()) return null;
        return requireInherited().getExplicitSummaryField(name);
    }
Returns the first explicit instance found of a summary field with this name, or null if not present explicitly in
any summary class

@param name the name of the explicit summary field to get.
@return the SummaryField found.
config-model/src/main/java/com/yahoo/schema/Schema.java