build.gradle

apply plugin: 'java-library'
apply plugin: 'com.google.protobuf'

sourceSets {
    main.java.srcDirs += "${protobuf.generatedFilesBaseDir}/main/javalite"
}

sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    api 'com.google.protobuf:protobuf-lite:3.0.1'
}

protobuf {
    protoc {
        // You still need protoc like in the non-Android case
        artifact = 'com.google.protobuf:protoc:3.0.0'
    }

    plugins {
        javalite {
            // The codegen for lite comes as a separate artifact
            artifact = 'com.google.protobuf:protoc-gen-javalite:3.0.0'
        }
    }

    generateProtoTasks {
        all().each { task ->
            task.builtins {
                // In most cases you don't need the full Java output
                // if you use the lite output.
                remove java
            }
            task.plugins {
                javalite {}
            }
        }
    }
}