public ModelAssembler addDocumentNode(Node document) {
        documentNodes.add(Objects.requireNonNull(document));
        return this;
    }
Adds a parsed JSON model file as a {@link Node} to the assembler.

@param document Parsed document node to add.
@return Returns the assembler.
smithy-model/src/main/java/software/amazon/smithy/model/loader/ModelAssembler.java