"Unresolved reference: http" Kotlin. Why does this happen?

Here is where it fails.

The full error message looks like this:

#12 55.48 [ERROR] Failed to execute goal org.jetbrains.kotlin:kotlin-maven-plugin:1.5.30:compile (compile) on project tool: Compilation failure #12 55.48 [ERROR] /workspace/app/src/main/kotlin/com/ob/tool/LoginController.kt:[7,17] Unresolved reference: http

package com.ob.tool

import org.apache.catalina.connector.Response
import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation.*
import java.net.http.HttpResponse

@RestController
class LoginController {

    @CrossOrigin(origins = ["http://localhost:8080"])
    @PostMapping("/login")
    fun login(@RequestBody user: User): ResponseEntity<Response> {
       return if(user.username == "Admin" && user.password == "Admin4040") ResponseEntity(HttpStatus.OK) else ResponseEntity(HttpStatus.UNAUTHORIZED)
    }

}

My Dockerfile/docker-compose looks like this:

FROM openjdk:8-jdk-alpine as build
WORKDIR /workspace/app

COPY mvnw .
COPY .mvn .mvn
COPY pom.xml .
COPY src src

RUN ./mvnw install -DskipTests
RUN mkdir -p target/dependency && (cd target/dependency; jar -xf ../*.jar)

FROM openjdk:8-jdk-alpine
VOLUME /tmp
ARG DEPENDENCY=/workspace/app/target/dependency
COPY --from=build ${DEPENDENCY}/BOOT-INF/lib /app/lib
COPY --from=build ${DEPENDENCY}/META-INF /app/META-INF
COPY --from=build ${DEPENDENCY}/BOOT-INF/classes /app
ENTRYPOINT ["java","-cp","app:app/lib/*","hello.Application"]

version: "3.5"

services:
  frontend:
    build: ./frontend
    ports:
      - "8080:8080"
    volumes:
      - ./frontend/src:/App/src

  backend:
    build: ./backend
    ports:
      - "8081:8081"
    volumes:
      - ./backend/src:/App/src