public void setValue(FieldValue value) {
        if ( ! type.getValueType().isAssignableFrom(value.getDataType()))
            throw new IllegalArgumentException("Got " + value.getDataType() + " but require " + type.getValueType());
        this.value = value;
    }
A field value which represents a map entry. Used to access map entries in for_each.

@author bratseth
indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/MapEntryFieldValue.java