content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * Calcite adapters.
   *
   * <p>An adapter allows Calcite to access data in a particular data source as
   * if it were a collection of tables in a schema. Each adapter typically
   * contains an implementation of {@link org.apache.calcite.schema.SchemaFactory}
   * and some classes that implement other schema SPIs.
   *
   * <p>To use an adapter, include a custom schema in a JSON model file:
   *
   * <blockquote><pre>
   *    schemas: [
   *      {
   *        type: 'custom',
   *        name: 'My Custom Schema',
   *        factory: 'com.acme.MySchemaFactory',
   *        operand: {a: 'foo', b: [1, 3.5] }
   *      }
   *   ]
   * </pre>
   * </blockquote>
   */
  @DefaultQualifier(value = NonNull.class, locations = TypeUseLocation.FIELD)
  @DefaultQualifier(value = NonNull.class, locations = TypeUseLocation.PARAMETER)
  @DefaultQualifier(value = NonNull.class, locations = TypeUseLocation.RETURN)
  package org.apache.calcite.adapter;
  
  import org.checkerframework.checker.nullness.qual.NonNull;
  import org.checkerframework.framework.qual.DefaultQualifier;
  import org.checkerframework.framework.qual.TypeUseLocation;
  