public static PowAlgorithm fromString(final String str) {
    for (final PowAlgorithm powAlgorithm : PowAlgorithm.values()) {
      if (powAlgorithm.name().equalsIgnoreCase(str)) {
        return powAlgorithm;
      }
    }
    return null;
  }
From string pow algorithm.

@param str pow algorithm as string
@return the pow algorithm interface. null if not valid enum.
config/src/main/java/org/hyperledger/besu/config/PowAlgorithm.java