Unable to build idea-2021.1.3

I am getting an error trying to build 2021.1.3. As the error appears to be in the android repo, let me say that I created a completely new clone of the android repo for this build, and I am using the master branch, as there is no matching tag idea/211.7628.21.

(Why is this tag not defined? Why has the practice of matching tags been stopped? How can one achieve reliable builds without them?)

Based on previous advice, I set these environment variables:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/amazon/amazon-corretto-11.jdk/Contents/Home
export JDK_18_x64=/Library/Java/JavaVirtualMachines/1.8.0.jdk/Contents/Home
export JDK_16_x64=/Library/Java/JavaVirtualMachines/1.8.0.jdk/Contents/Home

The apparent error:

/Volumes/A/MyIDEA/android/android-kotlin/android-extensions-idea-common/src/org/jetbrains/kotlin/android/synthetic/idea/res/IDEAndroidPackageFragmentProviderExtension.kt:30:
     [java] Overload resolution ambiguity: 
     [java] internal val [ERROR : ModuleInfo].androidExtensionsIsEnabled: Boolean defined in org.jetbrains.kotlin.android.synthetic.idea in file ExperimentalUtils.kt
     [java] internal val Module.androidExtensionsIsEnabled: Boolean defined in org.jetbrains.kotlin.android.synthetic.idea in file ExperimentalUtils.kt
     [java] /Volumes/A/MyIDEA/android/android-kotlin/android-extensions-idea-common/src/org/jetbrains/kotlin/android/synthetic/idea/res/IDEAndroidPackageFragmentProviderExtension.kt:38:
     [java] 'createLazyValue' overrides nothing
     [java] Compilation failed with exception: Compilation failed