public function __construct(
        MagentoCatalogModelResourceModelProductCollectionFactory $productCollectionFactory,
        MagentoCatalogApiDataProductSearchResultsInterfaceFactory $searchResultsFactory,
        MagentoFrameworkApiExtensionAttributeJoinProcessorInterface $extensionAttributesJoinProcessor) {

    $this->productCollection = $productCollectionFactory;
    $this->searchResultsFactory = $searchResultsFactory;
    $this->extensionAttributesJoinProcessor = $extensionAttributesJoinProcessor;
}

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return MagentoFrameworkApiSearchResults
 */
public function products($query) {

        $collection = $this->productCollection->create();
        $this->extensionAttributesJoinProcessor->process($collection);

        $collection->addAttributeToSelect('*');
        $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
        $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

        $collection->setCurPage(1);
        $collection->setPageSize(100);
        $collection->load();

        $searchResult = $this->searchResultsFactory->create();
        $searchResult->setItems($collection->getItems());
        $searchResult->setTotalCount($collection->getSize());

    return $searchResult;
}

public function getList(MagentoFrameworkApiSearchCriteriaInterface $searchCriteria)
{
    /** @var MagentoCatalogModelResourceModelProductCollection $collection */
    $collection = $this->collectionFactory->create();
    $this->extensionAttributesJoinProcessor->process($collection);

    foreach ($this->metadataService->getList($this->searchCriteriaBuilder->create())->getItems() as $metadata) {
        $collection->addAttributeToSelect($metadata->getAttributeCode());
    }
    $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
    $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

    //Add filters from root filter group to the collection
    foreach ($searchCriteria->getFilterGroups() as $group) {
        $this->addFilterGroupToCollection($group, $collection);
    }
    /** @var SortOrder $sortOrder */
    foreach ((array)$searchCriteria->getSortOrders() as $sortOrder) {
        $field = $sortOrder->getField();
        $collection->addOrder(
            $field,
            ($sortOrder->getDirection() == SortOrder::SORT_ASC) ? 'ASC' : 'DESC'
        );
    }
    $collection->setCurPage($searchCriteria->getCurrentPage());
    $collection->setPageSize($searchCriteria->getPageSize());
    $collection->load();

    $searchResult = $this->searchResultsFactory->create();
    $searchResult->setSearchCriteria($searchCriteria);
    $searchResult->setItems($collection->getItems());
    $searchResult->setTotalCount($collection->getSize());
    return $searchResult;
}

<preference for="tommyjsProductsApiProductsInterface"
            type="tommyjsProductsModelProductsEndpoint" />

<type name="tommyjsProductsModelProductsEndpoint">
    <arguments>
        <argument name="productCollectionFactory" xsi:type="object">MagentoCatalogModelResourceModelProductCollectionFactory</argument>
    </arguments>
</type>

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return MagentoFrameworkApiSearchResults
 */
public function products($query) {

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query.
 * @return MagentoCatalogApiDataProductSearchResultsInterface
 */
public function products($query) {

#vendor/magento/module-catalog/etc/webapi.xml

<route url="/V1/products1/:query" method="GET">
    <service class="MagentoCatalogApiProductRepositoryInterface" method="products1"/>
    <resources>
        <resource ref="anonymous" />
    </resources>
</route>


#vendor/magento/module-catalog/Api/ProductRepositoryInterface.php

/**
 * Return the sum of the two numbers.
 *
 * @api
 * @param string $query|null.
 * @return MagentoFrameworkApiSearchResults
 */
public function products1($query);


# vendor/magento/module-catalog/Model/ProductRepository.php

public function products1($query) {
    #MagentoCatalogModelResourceModelProductCollectionFactory $productCollection
    $collection = $this->productCollection->create();
    $this->extensionAttributesJoinProcessor->process($collection);

    $collection->addAttributeToSelect('*');
    $collection->joinAttribute('status', 'catalog_product/status', 'entity_id', null, 'inner');
    $collection->joinAttribute('visibility', 'catalog_product/visibility', 'entity_id', null, 'inner');

    $collection->setCurPage(1);
    $collection->setPageSize(100);
    $collection->load();

    $searchResult = $this->searchResultsFactory->create();
    $searchResult->setItems($collection->getItems());
    $searchResult->setTotalCount($collection->getSize());

    return $searchResult;
}