in powershell-server/src/main/java/jetbrains/buildServer/powershell/server/PowerShellRunType.java [201:207]
private String getRequirementPropertyName(@NotNull final List<String> keys) {
if (keys.size() == 1) {
return keys.get(0);
} else {
return RequirementQualifier.EXISTS_QUALIFIER + "(" + String.join("|", keys) + ")";
}
}