Hibernate tries to drop existing index

I’m having frequent database (SQLServer) deadlocks in my system, and it seems that they are related to when a scheduled job (a separate application) tries to access the database. At the same time a tomcat server is continually using the same database.
A suspected culprit is the process listed below, which tries to drop an existing index; my guess is that this happens when the scheduled job i starting. It is true that the ‘update’ option is currently used, but why should that cause an existing index to be dropped? I would understand if things missing are created, and indexes updated, but why drop an index?


[This is my first post; apologies if I haven’t listed something that I ought to.]

  <process id="processae00368c8" taskpriority="0" logused="604" waitresource="OBJECT: 8:629577281:0 " waittime="7502" ownerId="9307125645" transactionname="ALTER TABLE" lasttranstarted="2020-03-17T13:30:10.967" XDES="0x19cc97c420" lockMode="Sch-M" schedulerid="4" kpid="10856" status="suspended" spid="233" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2020-03-17T13:30:10.967" lastbatchcompleted="2020-03-17T13:30:10.963" lastattention="1900-01-01T00:00:00.963" clientapp="jTDS" hostname="xxx" hostpid="123" loginname="xxx" isolationlevel="read committed (2)" xactid="9307125645" currentdb="8" currentdbname="xxx" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
    <frame procname="adhoc" line="1" stmtend="118" sqlhandle="0x01000800f4d3e40c90bf72a50800000000000000000000000000000000000000000000000000000000000000">
alter table Leg drop constraint idx_6ty8d73kag4oa7363s4n4v88    </frame>
alter table Leg drop constraint idx_6ty8d73kag4oa7363s4n4v888   </inputbuf>