in src/main/java/org/apache/sling/testing/mock/caconfig/ConfigurationPersistHelper.java [119:126]
private String getNestedCollectionItemConfigName(@NotNull String configName, @NotNull String itemName, @NotNull String key) {
String nestedKey = configName + "/" + itemName + "/" + key;
String nestedConfigName = configurationPersistenceStrategy.getCollectionItemConfigName(nestedKey, null);
if (nestedConfigName == null) {
throw new IllegalArgumentException("Nested configuration not supported for " + nestedKey);
}
return nestedConfigName;
}