in src/main/java/ru/adelf/idea/dotenv/completion/NestedEnvVariableCompletionContributor.kt [34:42]
override fun addCompletions(parameters: CompletionParameters, context: ProcessingContext, result: CompletionResultSet) {
val position = parameters.position
val index = FileBasedIndex.getInstance()
val processor = CollectUniquesProcessor<String?>()
index.processAllKeys<String?>(DotEnvKeyValuesIndex.KEY, processor, position.getProject())
processor.getResults()
.filterNotNull()
.forEach { result.addElement(LookupElementBuilder.create(it)) }
}