java.time.Instant.getEpochSecond javadoc can be improved to be more specific.

The getNano method correctly specifies the return as: 'total number of nanoseconds from the second returned by getEpochSecond()"

However, the getEpochSecond javadoc says: "the nanosecond part of the day".
It should be "the nanosecond part of the second.".

Ref: http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-February/051232.html