public BindingType getOperationBindingType(ToShapeId resource, ToShapeId operation) {
        return Optional.ofNullable(bindingTypes.get(resource.toShapeId()))
                .flatMap(resourceMap -> Optional.ofNullable(resourceMap.get(operation.toShapeId())))
                .orElse(BindingType.NONE);
    }
Gets the identifier binding type of an operation to a resource.

<p>The NONE Binding type is returned if the resource can't be found,
the operation can't be found, or if the operation is not bound to the
resource.

@param resource Shape ID of a resource.
@param operation Shape ID of an operation.
@return Returns the binding type of the operation.
smithy-model/src/main/java/software/amazon/smithy/model/knowledge/IdentifierBindingIndex.java