content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  import java.util.Collections;
  import java.util.List;
  
  /**
   * Thrown when attempting to build a protocol message that is missing required fields. This is a
   * {@code RuntimeException} because it normally represents a programming error: it happens when some
   * code which constructs a message fails to set all the fields. {@code parseFrom()} methods <b>do
   * not</b> throw this; they throw an {@link InvalidProtocolBufferException} if required fields are
   * missing, because it is not a programming error to receive an incomplete message. In other words,
   * {@code UninitializedMessageException} should never be thrown by correct code, but {@code
   * InvalidProtocolBufferException} might be.
   *
   * @author kenton@google.com Kenton Varda
   */
  public class UninitializedMessageException extends RuntimeException {
    private static final long serialVersionUID = -7466929953374883507L;
  
    public UninitializedMessageException(final MessageLite message) {
      super(
          "Message was missing required fields.  (Lite runtime could not "
              + "determine which fields were missing).");
      missingFields = null;
    }
  
    public UninitializedMessageException(final List<String> missingFields) {
      super(buildDescription(missingFields));
      this.missingFields = missingFields;
    }
  
    private final List<String> missingFields;
  
    /**
     * Get a list of human-readable names of required fields missing from this message. Each name is a
     * full path to a field, e.g. "foo.bar[5].baz". Returns null if the lite runtime was used, since
     * it lacks the ability to find missing fields.
     */
    public List<String> getMissingFields() {
      return Collections.unmodifiableList(missingFields);
    }
  
    /**
     * Converts this exception to an {@link InvalidProtocolBufferException}. When a parsed message is
     * missing required fields, this should be thrown instead of {@code
     * UninitializedMessageException}.
     */
    public InvalidProtocolBufferException asInvalidProtocolBufferException() {
      return new InvalidProtocolBufferException(getMessage());
    }
  
    /** Construct the description string for this exception. */
    private static String buildDescription(final List<String> missingFields) {
      final StringBuilder description = new StringBuilder("Message missing required fields: ");
      boolean first = true;
      for (final String field : missingFields) {
        if (first) {
          first = false;
        } else {
          description.append(", ");
        }
        description.append(field);
      }
      return description.toString();
    }
  }
  