Spring Boot with overridden Spring Version (with dependency management)

build.gradle

buildscript {
    ext {
        springBootVersion = '1.2.5.RELEASE'
    }
    
    ext['spring.version'] = '4.2.1.RELEASE'
	
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}") 
        classpath("io.spring.gradle:dependency-management-plugin:0.5.3.RELEASE")
    }
}

apply plugin: 'java'
apply plugin: 'spring-boot' 
apply plugin: 'io.spring.dependency-management' 

jar {
    baseName = 'demo'
    version = '0.0.1-SNAPSHOT'
}
sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {    
    compile("org.springframework.boot:spring-boot-starter-web")
    testCompile("org.springframework.boot:spring-boot-starter-test") 
}

dependencyManagement {
    imports {
        mavenBom 'io.spring.platform:platform-bom:1.1.3.RELEASE'
    }
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.6'
}