code: public static boolean isValid(final String cssValue) {
          // TODO modify to make a strict validation
          if (cssValue == null || StringUtil.isBlank(cssValue)) {
              return false;
          }
  
          final String[] cssValueParts = StringUtil.splitBySpace(cssValue);
  
          FlexGrow flexGrow = null;
          FlexShrink flexShrink = null;
          FlexBasis flexBasis = null;
  
          for (final String eachPart : cssValueParts) {
              boolean invalid = true;
  
              if (flexGrow == null && FlexGrow.isValid(eachPart)) {
                  flexGrow = new FlexGrow(eachPart);
                  invalid = false;
              } else if (flexShrink == null && FlexShrink.isValid(eachPart)) {
                  flexShrink = new FlexShrink(eachPart);
                  invalid = false;
              } else if (flexBasis == null && FlexBasis.isValid(eachPart)) {
                  flexBasis = new FlexBasis(eachPart);
                  invalid = false;
              }
              if (invalid) {
                  return false;
              }
          }
  
          return flexGrow != null || flexShrink != null || flexBasis != null;
      }
docs: checks the given css value is valid for this class. It does't do a strict
  validation.
  
  @param cssValue
  @return
  @since 1.0.0
  @author WFF