* Add exception for unsupported SQL, incomplete rules and other exceptions.

* check style

* Decouple AuthenticationEngine and BackendConnection

* Decouple AuthenticationEngine and BackendConnection

* Refactor BackendResponse judge sequence of MySQLComQueryPacketExecutor

* Refactor BackendResponse judge sequence of MySQLComStmtExecuteExecutor

* Refactor BackendResponse judge sequence of PostgreSQLComBindExecutor

* Refactor BackendResponse judge sequence of PostgreSQLComQueryExecutor

* Refactor MySQLComQueryPacketExecutor

* Refactor MySQLComStmtExecuteExecutor

* Refactor PostgreSQLComBindExecutor

* Refactor PostgreSQLComQueryExecutor

* Decouple AuthenticationEngine and BackendConnection

* Decouple AuthenticationEngine and BackendConnection

* Unify userName to username

* Refactor CommandExecutorTask

* Refactor MySQLComQueryPacketExecutor.isQueryResponse

* Refactor MySQLComStmtExecuteExecutor.isQueryResponse

* Refactor PostgreSQLComBindExecutor.isQueryResponse

* Refactor PostgreSQLComQueryExecutor.isQueryResponse

* For code inspection

* For code inspection

* For code inspection

* Fix checkstyle

* Refactor OrderedSPIRegistry

* Make field as local if possible

* Add @SuppressWarnings("unchecked")

* Remove redundant throws

* Remove assertEquals

* Add genertic type

* Support PostgreSQL array type (#6408)

* Support PostgreSQL array type, unit test (#6408)

* Support PostgreSQL array type, follow review suggestion (#6408)

* add DefaultRawSQLExecutorCallback

* remove useless callback

* add RawProxyExecutor

* refactor ShardingSphereStatement & ShardingSpherePreparedStatement

* add QueryHeaderBuilder

* merge QueryHeader and ExecuteQueryHeader

* merge ExecuteResponse and ExecuteResult

* rename ExecuteResponse to ExecuteResult

* rename ExecuteResponse to ExecuteResult

* refactor org.apache.shardingsphere.infra.executor.sql.raw.execute.result

* remove DefaultRawSQLExecutorCallback

* refactor UpdateResponse

* Rename AbstractShardingJDBCDatabaseAndTableTest to AbstractShardingSphereDataSourceForShardingTest

* Rename AbstractShadowJDBCDatabaseAndTableTest to AbstractShardingSphereDataSourceForShadowTest

* Rename AbstractMasterSlaveJDBCTest to AbstractShardingSphereDataSourceForMasterSlaveTest

* Rename AbstractEncryptJDBCDatabaseAndTableTest to AbstractShardingSphereDataSourceForEncryptTest

* Rename ShardingProxyContext to ShardingSphereProxyContext

* Rename sharding-proxy to shardingsphere-proxy

* rename org.apache.shardingsphere.shardingproxy to org.apache.shardingsphere.proxy

* Rename shardingsphere-underlying to shardingsphere-infra

* Rename shardingsphere-infra's subprojects

* Rename shardingsphere-infra's subprojects

* rename package from org.apache.shardingsphere.underlying.common to org.apache.shardingsphere.infra

* rename package from org.apache.shardingsphere.underlying.executor to org.apache.shardingsphere.infra.executor

* rename package from org.apache.shardingsphere.underlying.merge to org.apache.shardingsphere.infra.merge

* rename package from org.apache.shardingsphere.underlying.route to org.apache.shardingsphere.infra.route

* rename package from org.apache.shardingsphere.underlying.rewrite to org.apache.shardingsphere.infra.rewrite

* rename shardingsphere-database-protocol to shardingsphere-db-protocol

* rename package org.apache.shardingsphere.database to org.apache.shardingsphere.db

* #3555, fix postgresql proxy return redundant command complete packet

* #3555, for comments

* refactor TableMetaData

* remove useless exception

* add ShardingTableMetadataLoader

* add RuleSchemaMetaDataLoader

* remove ShardingMetaDataLoader

* move metadata decorator and loader to schema package

* rename RuleMetaDataLoader to RuleTableMetaDataLoader

* add SPI for RuleTableMetaDataLoader

* move sharding-proxy-transport to shardingsphere-database-protocol

* rename sharding-proxy-transport to shardingsphere-database-protocol for maven module

* rename org.apache.shardingsphere.shardingproxy.transport to org.apache.shardingsphere.database.protocol

* upgrade java version from 7 to 8

* upgrade lambda expr for java8

* use java8 Optional instead of guava Optional

* use java8 Optional instead of guava Optional

This reverts commit 88de2f07.

Merger master into orchestration 5.x