BUG 6759 Fix bug when importing PMTables in Text type
BUG 6759 Fix bug when importing PMTables in Text type

With defalut value '' not allowed.

hitsumabushi/processmaker,baozhoutao/processmaker,hitsumabushi/processmaker,tomolimo/processmaker-server,baozhoutao/processmaker,baozhoutao/processmaker,baozhoutao/processmaker,colosa/processmaker,tomolimo/processmaker-server,tomolimo/processmaker-server,hitsumabushi/processmaker,baozhoutao/processmaker,hitsumabushi/processmaker,baozhoutao/processmaker,colosa/processmaker,colosa/processmaker,tomolimo/processmaker-server,hitsumabushi/processmaker,tomolimo/processmaker-server,colosa/processmaker,hitsumabushi/processmaker,tomolimo/processmaker-server,colosa/processmaker,colosa/processmaker