How to inject not null #RepositoryRestResource into #RestController - spring-boot

Question

In my GCP Endpoints project #RepositoryRestResource gets injected into the #RestController as null. As a result I get a NullPointer of course. How to inject the properly initiated repository into controller?
Repository class, controller, application and pom follow.
The repository:
package com.katamlek.gcp_crystalloids;
#RepositoryRestResource
public interface PostRepository extends DatastoreRepository<Post, Long> {
}
The controller.
package com.katamlek.gcp_crystalloids;
#Api
#RestController
public class PostController{
#Autowired
private PostRepository postRepository;
// dummy
#ApiMethod(path = "/hello", httpMethod = ApiMethod.HttpMethod.GET)
public DummyClass hello() {
return new DummyClass();
}
#ApiMethod(path = "/add", httpMethod = ApiMethod.HttpMethod.POST)
public Post post(#RequestBody Post post) {
return postRepository.save(post);
}
...
And the pom.xml.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.katamlek</groupId>
<artifactId>gcp_crystalloids</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>gcp_crystalloids</name>
<description>Demo project for Crystalloids</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.SR8</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-gcp-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-gcp-starter-storage</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-gcp-data-datastore</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-gcp-starter-data-datastore</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-framework-all</artifactId>
<version>2.2.1</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-management-control-appengine-all</artifactId>
<version>1.0.13</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
<!-- <dependency>-->
<!-- <groupId>javax.servlet</groupId>-->
<!-- <artifactId>javax.servlet-api</artifactId>-->
<!-- <version>3.1.0</version>-->
<!-- <type>jar</type>-->
<!-- <scope>provided</scope>-->
<!-- </dependency>-->
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>endpoints-framework-maven-plugin</artifactId>
<version>1.0.2</version>
<configuration>
<!-- plugin configuration -->
<hostname>gcpcrystalloids.appspot.com</hostname>
</configuration>
</plugin>
</plugins>
</build>
</project>
The application:
package com.katamlek.gcp_crystalloids;
#SpringBootApplication(scanBasePackages = {"com.katamlek"})
#EntityScan(basePackages = {"com.katamlek"})
#EnableDatastoreRepositories(basePackages = {"com.katamlek"})
public class GcpCrystalloidsApplication {
public static void main(String[] args) {
SpringApplication.run(GcpCrystalloidsApplication.class, args);
}
}