elk-util-parent/elk-util-collections/src/main/java/org/semanticweb/elk/util/collections/entryset/EntryCollection.java
public void addStructural(E entry) {
		if (entry.getNext() != null)
			throw new IllegalArgumentException(
					"The given entry should be fresh!");
		int h = entry.structuralHashCode();
		int i = indexFor(h, buckets.length);
		modCount++;
		E e = buckets[i];
		entry.setNext(e);
		buckets[i] = entry;
		if (size++ >= oversize)
			resize(2 * buckets.length);
	}
public void addStructural(E entry) {
		if (entry.getNext() != null)
			throw new IllegalArgumentException(
					"The given entry should be fresh!");
		int h = entry.structuralHashCode();
		int i = indexFor(h, buckets.length);
		modCount++;
		E e = buckets[i];
		entry.setNext(e);
		buckets[i] = entry;
		if (size++ >= oversize)
			resize(2 * buckets.length);
	}
Adds the given entry to this collection; the entry is added even if a
structurally equal entry (modulo {@link Entry#structuralHashCode()} and
{@link Entry#structuralEquals(Object)}) is already present in the
collection

@param entry
the entry to be inserted; it is not allowed to have linked
elements: {@link Entry#getNext()} should be {@code null}