code: protected static Citrus getCitrus(ExtensionContext extensionContext) {
          Assert.notNull(extensionContext, "ExtensionContext must not be null");
          return extensionContext.getRoot().getStore(NAMESPACE).getOrComputeIfAbsent(Citrus.class.getName(), key -> {
              if (citrus == null) {
                  citrus = Citrus.newInstance();
              }
              
              return citrus;
          }, Citrus.class);
      }
docs: Get the {@link Citrus} associated with the supplied {@code ExtensionContext}.
  @return the {@code Citrus} (never {@code null})