build.gradle

@CompileStatic
class PropertiesWriter extends DefaultTask {
    @Input
    final Property<String> key = project.objects.property(String).convention("someProperty")

    @Input
    final Property<String> value = project.objects.property(String).convention("someValue")

    @OutputFile
    final Provider<RegularFile> outputFile = project.layout.buildDirectory.file("out.properties")

    @TaskAction
    void writeFile() {
        outputFile.get().asFile.write("${key.get()}=${value.get()}")
    }
}

@CompileStatic
class AwesomeTask extends DefaultTask {
    @Input
    final Property<String> propertyName = project.objects.property(String).convention("someProperty")

    @Input
    final Property<String> value = project.objects.property(String)

    @TaskAction
    void printProperty() {
        println(value.get())
    }
}

def writeProperties = tasks.register("writeProperties", PropertiesWriter)
def readProperties = tasks.register("readProperties", AwesomeTask) {
    value.set(writeProperties.map {
        def props = new Properties()
        props.load(writeProperties.get().outputFile.get().asFile.newInputStream())
        props.get(propertyName.get())
    })
}