Computing a hashcode for an array is tricky. Typically you want a hashcode that depends on the value of each element in the array, but many of the common ways to do this actually return a hashcode based on the identity of the array rather than its contents.

This check flags attempts to compute a hashcode from an array that do not take the contents of the array into account. There are several ways to mess this up:

• Call the instance .hashCode() method on an array.

• Call the JDK method java.util.Objects#hashCode() with an argument of array type.

• Call the JDK method java.util.Objects#hash() or the Guava method com.google.common.base.Objects#hashCode() with multiple arguments, at least one of which is an array.

• Call the JDK method java.util.Objects#hash() or the Guava method com.google.common.base.Objects#hashCode() with a single argument of primitive array type. Because these are varags methods that take Object..., the primitive array is autoboxed into a single-element Object array, and these methods use the identity hashcode of the primitive array rather than examining its contents. Note that calling these methods on an argument of Object array type actually does the right thing because no boxing is needed.

Please use either java.util.Arrays#hashCode() (for single-dimensional arrays) or java.util.Arrays#deepHashCode() (for multidimensional arrays) to compute a hash value that depends on the contents of the array. If you really intended to compute the identity hash code, consider using java.lang.System#identityHashCode() instead for clarity.