Good Morning Pallavi.
Some other examples of 'date&time' functionality through java functions.
You can use a JavaScript expression similar to the following for the 'Maximum Value' form-date-field attribute:
$(new Date().getTime() + 31556952000)
Where 31556952000 is a year in milliseconds.
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As getTime() is in milliseconds you could use something like the following for the 'Minimum Value':
$(new Date().getTime() + 259200000)
Where, 3 x 86400000 (one day in ms) = 259200000
Thanks and kind regards, Louis van Amelsfort.