private void fillSummaryToFromSummaryField(Schema schema, SDField field, SummaryField summaryField) {
        SummaryTransform summaryTransform = summaryField.getTransform();
        if (summaryTransform.isDynamic() && summaryField.getSourceCount() > 2) {
            // Avoid writing to summary fields that have more than a single input field, as that is handled by the
            // summary rewriter in the search core.
            return;
        }
        if (summaryTransform.isDynamic()) {
            DataType fieldType = field.getDataType();
            if (!DynamicSummaryTransformUtils.isSupportedType(fieldType)) {
                warn(schema, field, "Dynamic summaries are only supported for fields of type " +
                        "string and array<string>, ignoring summary field '" + summaryField.getName() +
                        "' for sd field '" + field.getName() + "' of type " +
                        fieldType.getName() + ".");
            }
        }
    }
This processor modifies all indexing scripts so that they output to the owning field by default. It also prevents
any output expression from writing to any field except for the owning field. Finally, for <code>SummaryExpression</code>,
this processor expands to write all appropriate summary fields.

@author Simon Thoresen Hult
config-model/src/main/java/com/yahoo/schema/processing/IndexingOutputs.java