@Override
    public void process(boolean validate, boolean documentsOnly) {
        for (DocumentSummary docsum : schema.getSummariesInThis().values()) {
            if ( ! docsum.inherited().isEmpty()) continue; // Implicit fields are added to inheriting summaries through their parent
            addField(docsum, new SummaryField("rankfeatures", DataType.STRING, SummaryTransform.RANKFEATURES, docsum), validate);
            addField(docsum, new SummaryField("summaryfeatures", DataType.STRING, SummaryTransform.SUMMARYFEATURES, docsum), validate);
        }
    }
This processor adds all implicit summary fields to all registered document summaries. If another field has already
been registered with one of the implicit names, this processor will throw an {@link IllegalStateException}.
config-model/src/main/java/com/yahoo/schema/processing/ImplicitSummaryFields.java