MongoDB aggregation $let expression to Java Driver -

MongoDB aggregation $let expression to Java Driver -

i have next $let look :

{ "$let": { "vars": { "h": { "$hour": "$date" } }, "in": { "$cond": { "if": { "$lt": [ "$$h", 6 ] }, "then": "night", "else": { "$cond": { "if": { "$lt": [ "$$h", 12 ] }, "then": "morning", "else": { "$cond": { "if": { "$lt": [ "$$h", 18 ] }, "then": "afternoon", "else": "evening" } } } } } } } }

i unable figure out way convert shell operation java driver version. tried mongodb java driver docs , google unable find way it.

any help on java implementation same.

thank in advance!!!

java mongodb aggregation-framework mongo-java