code: public static Object concat(Object lhs, Object rhs) throws UtilEvalError {
          Class<?> lhsType = lhs.getClass();
          Class<?> rhsType = rhs.getClass();
          if ( Types.arrayDimensions(lhsType) != Types.arrayDimensions(rhsType) )
              throw new UtilEvalError("Cannot concat arrays with inconsistent dimensions."
                  + " Attempting to concat array of type " + StringUtil.typeString(lhs)
                  + " with array of type " + StringUtil.typeString(rhs) + ".");
          Class<?> toType = Types.getCommonType(
                  Types.arrayElementType(lhsType),
                  Types.arrayElementType(rhsType));
          int[] dims = dimensions(lhs);
          dims[0] = Array.getLength(lhs) + Array.getLength(rhs);
          Object toArray = Array.newInstance(toType, dims);
          copy(toType, toArray, lhs, rhs);
          return toArray;
      }
docs: Concatenate two arrays.
  @param lhs 1st array
  @param rhs 2nd array
  @return a new array instance of concatenated contents.
  @throws UtilEvalError for inconsistent dimensions.