}
  }

  /**
   * Incorporate additional requirements into an existing requirements object.
   *
   * @param requirements the existing requirements object
   * @param moreRequirements more requirements to incorporate
   * @param source the source of the additional requirements (used only for error reporting)
   * @return the existing requirements object, modified to include the additional requirements

                        .expectResult(MODULE_B),
                scenario("Selected missing project as required and as optional")
                        .activeRequiredProjects("non-existing-module")
                        .activeOptionalProjects("non-existing-module")
                        .expectResult(MavenExecutionException.class, "not find the selected project"),
                scenario("Resuming from project")

                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        element = mergePlugin(element, existing, sourceDominant, context);

                        master.put(key, element);

                        if (!pending.isEmpty()) {

            for (PluginExecution element : tgt) {
                Object key = getPluginExecutionKey().apply(element);
                PluginExecution existing = merged.get(key);
                if (existing != null) {
                    element = mergePluginExecution(element, existing, sourceDominant, context);
                }
                merged.put(key, element);
            }

            builder.executions(merged.values());

    // next map.get()
    when(backingMap.get(KEY)).thenReturn(existingZero);
    // since get returned zero, try a replace; that fails due to a simulated race
    when(backingMap.replace(eq(KEY), eq(existingZero), isA(AtomicInteger.class))).thenReturn(false);
    when(backingMap.putIfAbsent(eq(KEY), isA(AtomicInteger.class))).thenReturn(existing);

    // another map.get()

      } // else no check necessary, all index values are valid
      L existing = locks.get(index);
      if (existing != null) {
        return existing;
      }
      L created = supplier.get();
      existing = locks.putIfAbsent(index, created);
      return MoreObjects.firstNonNull(existing, created);
    }

    @Override
    public int size() {
      return size;
    }
  }

    // next map.get()
    when(backingMap.get(KEY)).thenReturn(existingZero);
    // since get returned zero, try a replace; that fails due to a simulated race
    when(backingMap.replace(eq(KEY), eq(existingZero), isA(AtomicInteger.class))).thenReturn(false);
    when(backingMap.putIfAbsent(eq(KEY), isA(AtomicInteger.class))).thenReturn(existing);

    // another map.get()

            }
            if ( !nonPooled && tc.getConfig().getSessionLimit() != 1 ) {
                SmbTransportImpl existing = findConnection(tc, address, port, localAddr, localPort, hostName, forceSigning, false);
                if ( existing != null ) {
                    return existing;
                }
            }

      Class<E> clazz) {
    Map<E, LockGraphNode> existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.get(clazz);
    if (existing != null) {
      return existing;
    }
    Map<E, LockGraphNode> created = createNodes(clazz);
    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
    return MoreObjects.firstNonNull(existing, created);
  }

  /**

    }
  }

  /**
   * Incorporate additional requirements into an existing requirements object.
   *
   * @param requirements the existing requirements object
   * @param moreRequirements more requirements to incorporate
   * @param source the source of the additional requirements (used only for error reporting)
   * @return the existing requirements object, modified to include the additional requirements