in core/src/main/java/com/google/cloud/sql/core/DnsInstanceConnectionNameResolver.java [40:57]
public CloudSqlInstanceName resolve(final String name) {
if (CloudSqlInstanceName.isValidInstanceName(name)) {
// name contains a well-formed instance name.
return new CloudSqlInstanceName(name);
}
if (CloudSqlInstanceName.isValidDomain(name)) {
// name contains a well-formed domain name.
return resolveDomainName(name);
}
// name is not well-formed, and therefore cannot be resolved.
throw new IllegalArgumentException(
String.format(
"Unable to resolve database instance for \"%s\". It should be a "
+ "well-formed instance name or domain name.",
name));
}