public boolean isGapIndex(BigInteger index) {
		if (BigInteger.ZERO.equals(index)) {
			return false;
		}
		if (index.compareTo(minIndex) > 0 && index.compareTo(maxIndex) < 0) {
			return false;
		}
		return isGapAddress(getAddress(index));
	}
Returns true if address of the given index is not the successor of the
previous index's address.

@param index the index to test for gap in the address set.
@return true if the given index represents the first address after a gap in the address set.
Ghidra/Features/Base/src/main/java/ghidra/app/util/viewer/util/AddressIndexMap.java