in src/main/java/software/amazon/msk/auth/iam/internals/MSKCredentialProvider.java [303:310]
private StsClientBuilder getStsClientBuilder(Region stsRegion, Boolean shouldUseFips) {
StsClientBuilder builder = StsClient.builder().region(stsRegion);
if (stsRegion != Region.AWS_GLOBAL && !shouldUseFips) {
log.debug("Using STS Endpoint override");
builder.endpointOverride(buildEndpointConfiguration(stsRegion));
}
return builder;
}