Spring Boot with overridden Spring Version (without dependency management)

build.gradle

buildscript {
    ext {
      springBootVersion = '1.2.5.RELEASE'
		  springVersion = '4.2.1.RELEASE'
    }
	
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}") 
    }
}

apply plugin: 'java'
apply plugin: 'spring-boot' 

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") 
}

configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        if (details.requested.group == 'org.springframework') {
            details.useVersion "${springVersion}"
        }
    }
}

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