public StructDataType getStructType(String name) {
        var mine = declaredStructTypes.get(name);
        if (mine != null) {
            return mine;
        }
        for (DocumentType inheritedType : inherits) {
            var fromParent = inheritedType.getStructType(name);
            if (fromParent == null) {
                continue;
            } else if (mine == null) {
                mine = fromParent;
            } else if (mine != fromParent) {
                throw new IllegalArgumentException("Found multiple conflicting struct types for "+name);
            }
        }
        return mine;
    }
Get a struct declared in this document (or any inherited
document). Returns null if no such struct was found.
If multiple possible structs are found in inherited
documents, throws exception.

@param name the name of the struct
@return reference to a struct data type, or null
document/src/main/java/com/yahoo/document/DocumentType.java