解决因生成javadoc失败导致Maven打包失败问题

方案就是设置javadoc生成失败时不导致整个打包失败：

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <version>2.8</version>
                <executions>
                    <execution>
                        <id>attach-javadocs</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                        <configuration>
                            <failOnError>false</failOnError>
                        </configuration>
                    </execution>
                </executions>
            </plugin>