following the instructions on the kotlin gradle page I have this code

tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
    kotlinOptions {
        suppressWarnings = true
        jvmTarget = "1.8"
    }
}

but it's resulting in this error.

* What went wrong:
Script compilation errors:

  Line 35: tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
                                                            ^ Classifier 'KotlinCompile' does not have a companion object, and thus must be initialized here

  Line 36:     kotlinOptions {
               ^ Unresolved reference: kotlinOptions

  Line 37:         suppressWarnings = true
                   ^ Unresolved reference: suppressWarnings

  Line 38:         jvmTarget = "1.8"
                   ^ Unresolved reference: jvmTarget