I'm working on a Spring Boot app with multiple modules and we're using Gradle to build it. Unfortunately I can't get the Gradle configuration right. 

The project structure is this:

```
parent
  |
  + build.gradle
  |
  + settings.gradle
  |
  + core
  |   |
  |   + build.gradle
  | 
  + apis
  |   |
  |   + build.gradle
  |
  + services
  |   |
  |   + build.gradle
  | 
  + data
  |   |
  |   + build.gradle

```

When I try to build the project, I get compilation errors like `error: cannot find symbol` saying, that the classes from data used in services aren't imported. And I assume this is true between all the modules.

My parent build.gradle looks like this:

```
buildscript {
    ext {
        springBootVersion = '2.0.0.BUILD-SNAPSHOT'
    }
    repositories {
        mavenCentral()
        maven { url "https://repo.spring.io/snapshot" }
        maven { url "https://repo.spring.io/milestone" }
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'eclipse'
apply plugin: 'idea'

allprojects {
    apply plugin: 'java'
    apply plugin: 'org.springframework.boot'
    apply plugin: 'io.spring.dependency-management'

    group = 'com.example'
    version = '0.0.1-SNAPSHOT'
    sourceCompatibility = 1.8
    targetCompatibility = 1.8

    repositories {
        mavenCentral()
        maven { url "https://repo.spring.io/snapshot" }
        maven { url "https://repo.spring.io/milestone" }
    }

    dependencies {
        testCompile('org.springframework.boot:spring-boot-starter-test')
    }
}

dependencies {
    compile project(':data')
    compile project(':services')
    compile project(':apis')
    compile project(':core')
}

jar {
    baseName = 'my-jar'
    version = '0.0.1-SNAPSHOT'
}

```

settings.gradle:

```
rootProject.name = 'my-app'
include ':apis'
include ':core'
include ':data'
include ':services'

```

one of children (core) has this in it's build.gradle:

```
dependencies {
    compile('org.springframework.boot:spring-boot-starter-actuator')
    compile('org.springframework.boot:spring-boot-starter-quartz')
    compile('org.springframework.boot:spring-boot-starter-tomcat')
    runtime('com.h2database:h2')

    compile project(':data')
    compile project(':services')
    compile project(':apis')
}

```

services build.gradle looks like this:

```
dependencies {
    compile('org.springframework.boot:spring-boot-starter-quartz')
    compile('org.springframework.boot:spring-boot-starter-data-jpa')
    runtime('com.h2database:h2')

    compile project(':data')
}

```

The other ones also declare only dependencies.

The dependency structure looks like this:

```
core - apis, services, data

apis - services, data

services - data

data -

```

Example of the compilation errors:

```
/my-app/services/src/main/java/com/example/my-app/business/IssuedTokenService.java:3: error: package com.examples.data.dao does not exist import com.examples.data.dao.IssuedToken;

/my-app/services/src/main/java/com/example/my-app/business/IssuedTokenService.java:4: error: package com.examples.data.repository does not exist import com.examples.data.repository.IssuedTokenRepository;

/my-app/services/src/main/java/com/example/my-app/business/IssuedTokenService.java:12: error: cannot find symbol 
    private IssuedTokenRepository issuedTokenRepository;

    symbol:   class IssuedTokenRepository
   location: class IssuedTokenService

/my-app/services/src/main/java/com/example/my-app/business/IssuedTokenService.java:15: error: cannot find symbol
   public void saveToken(IssuedToken issuedToken) {
                                  ^
   symbol:   class IssuedToken
   location: class IssuedTokenService

```