code: protected void checkInputParameters(final IChemObjectBuilder builder,
                                          final double minMass, final double maxMass,
                                          final MolecularFormulaRange mfRange) {
          if ((minMass < 0.0) || (maxMass < 0.0)) {
              throw (new IllegalArgumentException(
                      "The minimum and maximum mass values must be >=0"));
          }
  
          if ((minMass > maxMass)) {
              throw (new IllegalArgumentException(
                      "Minimum mass must be <= maximum mass"));
          }
  
          if ((mfRange == null) || (mfRange.getIsotopeCount() == 0)) {
              throw (new IllegalArgumentException(
                      "The MolecularFormulaRange parameter must be non-null and must contain at least one isotope"));
          }
  
          // Sort the elements by mass in ascending order. That speeds up
          // the search.
          for (IIsotope isotope : mfRange.isotopes()) {
              // Check if exact mass of each isotope is set
              if (isotope.getExactMass() == null)
                  throw new IllegalArgumentException(
                          "The exact mass value of isotope " + isotope
                                  + " is not set");
          }
      }
docs: Checks if input parameters are valid and throws an IllegalArgumentException otherwise.