fix user reported NullPointerException

flow: Created branch 'hotfix/fix-report'.

Added tag v1.6.0 for changeset f3e8c9f56aa8

flow: Merged <release> '1.6.0' to <master> ('default').

flow: Merged <release> '1.6.0' to <develop> ('develop').

flow: Closed <release> '1.6.0'.

update version to 35/1.6.0

flow: Created branch 'release/1.6.0'.

flow: Merged <feature> 'zh-candidates' to <develop> ('develop').

flow: Closed <feature> 'zh-candidates'.

upgrade dependency and fix test

add preference dict_hanji_switch

fix migration for weight of words

fix index migration

migrate weight of words

fix database upgrade

add han candidates

move from android.support to androidx

update IDE and SDK

IDE and SDK upgrade

flow: Created branch 'feature/zh-candidates'.

add FindSecBugs

cleanup static code analysis

fix SpotBugs task

add SpotBugs

upgrade spring-boot

add checkstyle

do not fail when Dependency-Check report error

generate Dependency-Check report

add OWASP Dependency-Check

add PMD with CPD

Added tag v1.5.6 for changeset 24d0353d3041

flow: Merged <release> '1.5.6' to <master> ('default').

flow: Merged <release> '1.5.6' to <develop> ('develop').

flow: Closed <release> '1.5.6'.

jenkins: fix parameter

update version code to 29