require(type is KtFe10Type)
        return TypeUtils.isNullableType(type.fe10Type)
    }

    override fun isDenotable(type: KtType): Boolean {
        require(type is KtFe10Type)
        val kotlinType = type.fe10Type
        return kotlinType.isDenotable()
    }

    override fun isArrayOrPrimitiveArray(type: KtType): Boolean {
        require(type is KtFe10Type)

    }

    private fun isSubClassOf(subClass: KtClassOrObjectSymbol, superClass: KtClassOrObjectSymbol, allowIndirectSubtyping: Boolean): Boolean {
        require(subClass is KtFirSymbol<*>)
        require(superClass is KtFirSymbol<*>)

        if (subClass == superClass) return false
        return isSubClassOf(
            subClass = subClass.firSymbol.fir as FirClass,

      // seconds are not supported by this syntax.
      require(year >= 1601)
      require(month != -1)
      require(dayOfMonth in 1..31)
      require(hour in 0..23)
      require(minute in 0..59)
      require(second in 0..59)

      GregorianCalendar(UTC).apply {
        isLenient = false
        set(Calendar.YEAR, year)

      apply {
        val maxAgeSeconds = maxAge.inWholeSeconds
        require(maxAgeSeconds >= 0) { "maxAge < 0: $maxAgeSeconds" }
        this.maxAgeSeconds = maxAgeSeconds.commonClampToInt()
      }

    fun maxStale(maxStale: Duration) =
      apply {
        val maxStaleSeconds = maxStale.inWholeSeconds
        require(maxStaleSeconds >= 0) { "maxStale < 0: $maxStaleSeconds" }

  return null
}

internal fun Headers.Builder.commonBuild(): Headers = Headers(namesAndValues.toTypedArray())

internal fun headersCheckName(name: String) {
  require(name.isNotEmpty()) { "name is empty" }
  for (i in name.indices) {
    val c = name[i]
    require(c in '\u0021'..'\u007e') {
      "Unexpected char 0x${c.charCode()} at $i in header name: $name"
    }
  }
}

internal fun headersCheckValue(

    override fun getInheritorsOfSealedClass(
        classSymbol: KtNamedClassOrObjectSymbol
    ): List<KtNamedClassOrObjectSymbol> {
        require(classSymbol.modality == Modality.SEALED)
        require(classSymbol is KtFirNamedClassOrObjectSymbol)

        val inheritorClassIds = classSymbol.firSymbol.fir.getSealedClassInheritors(analysisSession.useSiteSession)

    flags: Int,
  ) {
    if (type != TYPE_WINDOW_UPDATE && logger.isLoggable(FINE)) {
      logger.fine(frameLog(false, streamId, length, type, flags))
    }
    require(length <= maxFrameSize) { "FRAME_SIZE_ERROR length > $maxFrameSize: $length" }
    require(streamId and 0x80000000.toInt() == 0) { "reserved bit set: $streamId" }
    sink.writeMedium(length)
    sink.writeByte(type and 0xff)
    sink.writeByte(flags and 0xff)

## Features requiring API changes

If a PR change requires an API change
* Updates to documentation do not require explicit approval from the Technical Oversight Committee (TOC). This can be
  held off after the release. Hiding/Showing documentation does not require TOC approval.
* Cases for other API changes require TOC approval

        require(this is TypeConstructor)
        return when (this) {
            is NewTypeVariableConstructor -> originalTypeParameter != null
            else -> declarationDescriptor is TypeParameterDescriptor
        }
    }

    override fun TypeConstructorMarker.asTypeParameter(): TypeParameterMarker {
        require(this is TypeConstructor)
        return when (this) {

        require(type is KtFirType)
        val coneType = type.coneType
        val substitutor = EnhancedForWarningConeSubstitutor(typeContext)
        val enhancedConeType = substitutor.substituteType(coneType)

        return enhancedConeType?.asKtType()
    }

    override fun buildSelfClassType(symbol: KtNamedClassOrObjectSymbol): KtType {
        require(symbol is KtFirNamedClassOrObjectSymbol)