final Mappings mappingsOf(final Class<?> clazz) {
        if (!mappings.containsKey(clazz)) {
            mappings.putIfAbsent(clazz, new Mappings(clazz));
        }
        return mappings.get(clazz);
    }
Gets the mapping definition for a given class.
@param clazz The class.
@return The mapping definition.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/DynamoDBMappingsRegistry.java