fix: update default values to be null where possible

Author: bryantbiggs

README.md

@@ -243,10 +243,10 @@ Users have the ability to:
 | <a name="input_backup_retention_period"></a> [backup\_retention\_period](#input\_backup\_retention\_period) | The days to retain backups for | `number` | `null` | no |
 | <a name="input_backup_window"></a> [backup\_window](#input\_backup\_window) | The daily time range (in UTC) during which automated backups are created if they are enabled. Example: '09:46-10:16'. Must not overlap with maintenance\_window | `string` | `null` | no |
 | <a name="input_ca_cert_identifier"></a> [ca\_cert\_identifier](#input\_ca\_cert\_identifier) | Specifies the identifier of the CA certificate for the DB instance | `string` | `null` | no |
-| <a name="input_character_set_name"></a> [character\_set\_name](#input\_character\_set\_name) | (Optional) The character set name to use for DB encoding in Oracle instances. This can't be changed. See Oracle Character Sets Supported in Amazon RDS and Collations and Character Sets for Microsoft SQL Server for more information. This can only be set on creation | `string` | `null` | no |
+| <a name="input_character_set_name"></a> [character\_set\_name](#input\_character\_set\_name) | The character set name to use for DB encoding in Oracle instances. This can't be changed. See Oracle Character Sets Supported in Amazon RDS and Collations and Character Sets for Microsoft SQL Server for more information. This can only be set on creation | `string` | `null` | no |
 | <a name="input_copy_tags_to_snapshot"></a> [copy\_tags\_to\_snapshot](#input\_copy\_tags\_to\_snapshot) | On delete, copy all Instance tags to the final snapshot | `bool` | `false` | no |
 | <a name="input_create_db_instance"></a> [create\_db\_instance](#input\_create\_db\_instance) | Whether to create a database instance | `bool` | `true` | no |
-| <a name="input_create_db_option_group"></a> [create\_db\_option\_group](#input\_create\_db\_option\_group) | (Optional) Create a database option group | `bool` | `true` | no |
+| <a name="input_create_db_option_group"></a> [create\_db\_option\_group](#input\_create\_db\_option\_group) | Create a database option group | `bool` | `true` | no |
 | <a name="input_create_db_parameter_group"></a> [create\_db\_parameter\_group](#input\_create\_db\_parameter\_group) | Whether to create a database parameter group | `bool` | `true` | no |
 | <a name="input_create_db_subnet_group"></a> [create\_db\_subnet\_group](#input\_create\_db\_subnet\_group) | Whether to create a database subnet group | `bool` | `false` | no |
 | <a name="input_create_monitoring_role"></a> [create\_monitoring\_role](#input\_create\_monitoring\_role) | Create IAM role with a defined name that permits RDS to send enhanced monitoring metrics to CloudWatch Logs | `bool` | `false` | no |
@@ -256,7 +256,7 @@ Users have the ability to:
 | <a name="input_db_name"></a> [db\_name](#input\_db\_name) | The DB name to create. If omitted, no database is created initially | `string` | `null` | no |
 | <a name="input_db_option_group_tags"></a> [db\_option\_group\_tags](#input\_db\_option\_group\_tags) | Additional tags for the DB option group | `map(string)` | `{}` | no |
 | <a name="input_db_parameter_group_tags"></a> [db\_parameter\_group\_tags](#input\_db\_parameter\_group\_tags) | Additional tags for the  DB parameter group | `map(string)` | `{}` | no |
-| <a name="input_db_subnet_group_description"></a> [db\_subnet\_group\_description](#input\_db\_subnet\_group\_description) | Description of the DB subnet group to create | `string` | `""` | no |
+| <a name="input_db_subnet_group_description"></a> [db\_subnet\_group\_description](#input\_db\_subnet\_group\_description) | Description of the DB subnet group to create | `string` | `null` | no |
 | <a name="input_db_subnet_group_name"></a> [db\_subnet\_group\_name](#input\_db\_subnet\_group\_name) | Name of DB subnet group. DB instance will be created in the VPC associated with the DB subnet group. If unspecified, will be created in the default VPC | `string` | `null` | no |
 | <a name="input_db_subnet_group_tags"></a> [db\_subnet\_group\_tags](#input\_db\_subnet\_group\_tags) | Additional tags for the DB subnet group | `map(string)` | `{}` | no |
 | <a name="input_db_subnet_group_use_name_prefix"></a> [db\_subnet\_group\_use\_name\_prefix](#input\_db\_subnet\_group\_use\_name\_prefix) | Determines whether to use `subnet_group_name` as is or create a unique name beginning with the `subnet_group_name` as the prefix | `bool` | `true` | no |
@@ -265,9 +265,9 @@ Users have the ability to:
 | <a name="input_domain"></a> [domain](#input\_domain) | The ID of the Directory Service Active Directory domain to create the instance in | `string` | `null` | no |
 | <a name="input_domain_iam_role_name"></a> [domain\_iam\_role\_name](#input\_domain\_iam\_role\_name) | (Required if domain is provided) The name of the IAM role to be used when making API calls to the Directory Service | `string` | `null` | no |
 | <a name="input_enabled_cloudwatch_logs_exports"></a> [enabled\_cloudwatch\_logs\_exports](#input\_enabled\_cloudwatch\_logs\_exports) | List of log types to enable for exporting to CloudWatch logs. If omitted, no logs will be exported. Valid values (depending on engine): alert, audit, error, general, listener, slowquery, trace, postgresql (PostgreSQL), upgrade (PostgreSQL) | `list(string)` | `[]` | no |
-| <a name="input_engine"></a> [engine](#input\_engine) | The database engine to use | `string` | `""` | no |
+| <a name="input_engine"></a> [engine](#input\_engine) | The database engine to use | `string` | `null` | no |
 | <a name="input_engine_version"></a> [engine\_version](#input\_engine\_version) | The engine version to use | `string` | `null` | no |
-| <a name="input_family"></a> [family](#input\_family) | The family of the DB parameter group | `string` | `""` | no |
+| <a name="input_family"></a> [family](#input\_family) | The family of the DB parameter group | `string` | `null` | no |
 | <a name="input_final_snapshot_identifier_prefix"></a> [final\_snapshot\_identifier\_prefix](#input\_final\_snapshot\_identifier\_prefix) | The name which is prefixed to the final snapshot on cluster destroy | `string` | `"final"` | no |
 | <a name="input_iam_database_authentication_enabled"></a> [iam\_database\_authentication\_enabled](#input\_iam\_database\_authentication\_enabled) | Specifies whether or not the mappings of AWS Identity and Access Management (IAM) accounts to database accounts are enabled | `bool` | `false` | no |
 | <a name="input_identifier"></a> [identifier](#input\_identifier) | The name of the RDS instance, if omitted, Terraform will assign a random, unique identifier | `string` | n/a | yes |
@@ -276,19 +276,19 @@ Users have the ability to:
 | <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | The ARN for the KMS encryption key. If creating an encrypted replica, set this to the destination KMS ARN. If storage\_encrypted is set to true and kms\_key\_id is not specified the default KMS key created in your account will be used | `string` | `null` | no |
 | <a name="input_license_model"></a> [license\_model](#input\_license\_model) | License model information for this DB instance. Optional, but required for some DB engines, i.e. Oracle SE1 | `string` | `null` | no |
 | <a name="input_maintenance_window"></a> [maintenance\_window](#input\_maintenance\_window) | The window to perform maintenance in. Syntax: 'ddd:hh24:mi-ddd:hh24:mi'. Eg: 'Mon:00:00-Mon:03:00' | `string` | `null` | no |
-| <a name="input_major_engine_version"></a> [major\_engine\_version](#input\_major\_engine\_version) | Specifies the major version of the engine that this option group should be associated with | `string` | `""` | no |
+| <a name="input_major_engine_version"></a> [major\_engine\_version](#input\_major\_engine\_version) | Specifies the major version of the engine that this option group should be associated with | `string` | `null` | no |
 | <a name="input_max_allocated_storage"></a> [max\_allocated\_storage](#input\_max\_allocated\_storage) | Specifies the value for Storage Autoscaling | `number` | `0` | no |
 | <a name="input_monitoring_interval"></a> [monitoring\_interval](#input\_monitoring\_interval) | The interval, in seconds, between points when Enhanced Monitoring metrics are collected for the DB instance. To disable collecting Enhanced Monitoring metrics, specify 0. The default is 0. Valid Values: 0, 1, 5, 10, 15, 30, 60 | `number` | `0` | no |
 | <a name="input_monitoring_role_arn"></a> [monitoring\_role\_arn](#input\_monitoring\_role\_arn) | The ARN for the IAM role that permits RDS to send enhanced monitoring metrics to CloudWatch Logs. Must be specified if monitoring\_interval is non-zero | `string` | `null` | no |
 | <a name="input_monitoring_role_description"></a> [monitoring\_role\_description](#input\_monitoring\_role\_description) | Description of the monitoring IAM role | `string` | `null` | no |
 | <a name="input_monitoring_role_name"></a> [monitoring\_role\_name](#input\_monitoring\_role\_name) | Name of the IAM role which will be created when create\_monitoring\_role is enabled | `string` | `"rds-monitoring-role"` | no |
 | <a name="input_multi_az"></a> [multi\_az](#input\_multi\_az) | Specifies if the RDS instance is multi-AZ | `bool` | `false` | no |
-| <a name="input_option_group_description"></a> [option\_group\_description](#input\_option\_group\_description) | The description of the option group | `string` | `""` | no |
+| <a name="input_option_group_description"></a> [option\_group\_description](#input\_option\_group\_description) | The description of the option group | `string` | `null` | no |
 | <a name="input_option_group_name"></a> [option\_group\_name](#input\_option\_group\_name) | Name of the option group | `string` | `null` | no |
-| <a name="input_option_group_timeouts"></a> [option\_group\_timeouts](#input\_option\_group\_timeouts) | Define maximum timeout for deletion of `aws_db_option_group` resource | `map(string)` | <pre>{<br>  "delete": "15m"<br>}</pre> | no |
+| <a name="input_option_group_timeouts"></a> [option\_group\_timeouts](#input\_option\_group\_timeouts) | Define maximum timeout for deletion of `aws_db_option_group` resource | `map(string)` | `{}` | no |
 | <a name="input_option_group_use_name_prefix"></a> [option\_group\_use\_name\_prefix](#input\_option\_group\_use\_name\_prefix) | Determines whether to use `option_group_name` as is or create a unique name beginning with the `option_group_name` as the prefix | `bool` | `true` | no |
 | <a name="input_options"></a> [options](#input\_options) | A list of Options to apply | `any` | `[]` | no |
-| <a name="input_parameter_group_description"></a> [parameter\_group\_description](#input\_parameter\_group\_description) | Description of the DB parameter group to create | `string` | `""` | no |
+| <a name="input_parameter_group_description"></a> [parameter\_group\_description](#input\_parameter\_group\_description) | Description of the DB parameter group to create | `string` | `null` | no |
 | <a name="input_parameter_group_name"></a> [parameter\_group\_name](#input\_parameter\_group\_name) | Name of the DB parameter group to associate or create | `string` | `null` | no |
 | <a name="input_parameter_group_use_name_prefix"></a> [parameter\_group\_use\_name\_prefix](#input\_parameter\_group\_use\_name\_prefix) | Determines whether to use `parameter_group_name` as is or create a unique name beginning with the `parameter_group_name` as the prefix | `bool` | `true` | no |
 | <a name="input_parameters"></a> [parameters](#input\_parameters) | A list of DB parameters (map) to apply | `list(map(string))` | `[]` | no |
@@ -309,8 +309,8 @@ Users have the ability to:
 | <a name="input_storage_type"></a> [storage\_type](#input\_storage\_type) | One of 'standard' (magnetic), 'gp2' (general purpose SSD), or 'io1' (provisioned IOPS SSD). The default is 'io1' if iops is specified, 'gp2' if not | `string` | `null` | no |
 | <a name="input_subnet_ids"></a> [subnet\_ids](#input\_subnet\_ids) | A list of VPC subnet IDs | `list(string)` | `[]` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | A mapping of tags to assign to all resources | `map(string)` | `{}` | no |
-| <a name="input_timeouts"></a> [timeouts](#input\_timeouts) | (Optional) Updated Terraform resource management timeouts. Applies to `aws_db_instance` in particular to permit resource management times | `map(string)` | <pre>{<br>  "create": "40m",<br>  "delete": "40m",<br>  "update": "80m"<br>}</pre> | no |
-| <a name="input_timezone"></a> [timezone](#input\_timezone) | (Optional) Time zone of the DB instance. timezone is currently only supported by Microsoft SQL Server. The timezone can only be set on creation. See MSSQL User Guide for more information | `string` | `null` | no |
+| <a name="input_timeouts"></a> [timeouts](#input\_timeouts) | Updated Terraform resource management timeouts. Applies to `aws_db_instance` in particular to permit resource management times | `map(string)` | `{}` | no |
+| <a name="input_timezone"></a> [timezone](#input\_timezone) | Time zone of the DB instance. timezone is currently only supported by Microsoft SQL Server. The timezone can only be set on creation. See MSSQL User Guide for more information | `string` | `null` | no |
 | <a name="input_username"></a> [username](#input\_username) | Username for the master DB user | `string` | `null` | no |
 | <a name="input_vpc_security_group_ids"></a> [vpc\_security\_group\_ids](#input\_vpc\_security\_group\_ids) | List of VPC security groups to associate | `list(string)` | `null` | no |