src/java.base/share/classes/java/lang/invoke/MethodHandle.java

@@ -884,13 +884,17 @@
      * Before calling the target, the adapter verifies that the array
      * contains exactly enough elements to provide a correct argument count
      * to the target method handle.
      * (The array may also be null when zero elements are required.)
      * <p>
-     * If, when the adapter is called, the supplied array argument does
-     * not have the correct number of elements, the adapter will throw
-     * an {@link IllegalArgumentException} instead of invoking the target.
+     * When the adapter is called, the length of the supplied {@code array}
+     * argument is queried as if by {@code array.length} or {@code arraylength}
+     * bytecode. If the adapter accepts zero-length trailing array argument,
+     * the supplied {@code array} argument can either be a zero-length array or
+     * {@code null}; otherwise, the adapter will throw a {@code NullPointerException}
+     * if {@code array} is {@code null} and throw an {@link IllegalArgumentException}
+     * if {@code array} does not have the correct number of elements.
      * <p>
      * Here are some simple examples of array-spreading method handles:
      * <blockquote><pre>{@code
 MethodHandle equals = publicLookup()
   .findVirtual(String.class, "equals", methodType(boolean.class, Object.class));