The left-hand side and right-hand side of this assignment are the same. It has no effect.
This also handles assignments in which the right-hand side is a call to Preconditions.checkNotNull(), which returns the variable that was checked for non-nullity. If you just intended to check that the variable is non-null, please don’t assign the result to the checked variable; just call Preconditions.checkNotNull() as a bare statement.
Suppress false positives by adding the suppression annotation @SuppressWarnings("SelfAssignment") to the enclosing element.