For `POST _license/start_basic` the API, the system decides whether a new basic license should be generated using the following logic:

https://github.com/elastic/elasticsearch/blob/3c15e4ebb1ae045d5cc690a0fd1e2f3c73173d39/x-pack/plugin/core/src/main/java/org/elasticsearch/license/StartBasicClusterTask.java#L101-L106

However, when building the response, the logic only takes account into old license type without checking maxNodes and expiryDate:

https://github.com/elastic/elasticsearch/blob/3c15e4ebb1ae045d5cc690a0fd1e2f3c73173d39/x-pack/plugin/core/src/main/java/org/elasticsearch/license/StartBasicClusterTask.java#L64-L65

This means it is possible that client gets an error response of 
```json
{
  "acknowledged": true,
  "basic_was_started": false,
  "error_message": "Operation failed: Current license is basic."
}
```
while the license is actually generated successfully at the backend. 

See also: https://github.com/elastic/elasticsearch/pull/85993#discussion_r859356499
x-pack/plugin/core/src/test/java/org/elasticsearch/license/LicenseServiceTests.java
public void testLogExpirationWarning() {
        long time = LocalDate.of(2018, 11, 15).atStartOfDay(ZoneOffset.UTC).toInstant().toEpochMilli();
        final boolean expired = randomBoolean();
        final String message = LicenseService.buildExpirationMessage(time, expired).toString();
        if (expired) {
            assertThat(message, startsWith("LICENSE [EXPIRED] ON [THURSDAY, NOVEMBER 15, 2018].\n"));
        } else {
            assertThat(message, startsWith("License [will expire] on [Thursday, November 15, 2018].\n"));