public ByteSource nextBytes() {
        return nextBytes(getDefaultNextBytesSize());
    }
Sets the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}. Defaults to
{@code 16}, which equals 128 bits, a size commonly used in cryptographic algorithms.

@param defaultNextBytesSize the size of the generated byte array for calls to {@link #nextBytes() nextBytes()}.
@throws IllegalArgumentException if the argument is 0 or negative
crypto/core/src/main/java/org/apache/shiro/crypto/SecureRandomNumberGenerator.java