### Question:
ConfigBuilder { static Path toPath(final String workDir, final String value) { if (workDir != null && value != null) { return Paths.get(workDir, value); } else if (value != null) { return Paths.get(value); } return null; } private  ConfigBuilder(); static ConfigBuilder create(); ConfigBuilder sslServerTrustMode(SslTrustMode sslServerTrustMode); ConfigBuilder sslClientTrustMode(SslTrustMode sslClientTrustMode); ConfigBuilder sslServerKeyStorePath(String sslServerKeyStorePath); ConfigBuilder sslServerTrustStorePath(String sslServerTrustStorePath); ConfigBuilder sslServerTrustCertificates(List<String> sslServerTrustCertificates); ConfigBuilder sslClientTrustStorePassword(char[] sslClientTrustStorePassword); ConfigBuilder unixSocketFile(String unixSocketFile); ConfigBuilder serverHostname(String serverHostname); ConfigBuilder serverPort(Integer serverPort); ConfigBuilder jdbcConfig(JdbcConfig jdbcConfig); ConfigBuilder peers(List<String> peers); ConfigBuilder alwaysSendTo(List<String> alwaysSendTo); ConfigBuilder sslKnownClientsFile(String knownClientsFile); ConfigBuilder sslKnownServersFile(String knownServersFile); ConfigBuilder sslAuthenticationMode(SslAuthenticationMode sslAuthenticationMode); ConfigBuilder sslClientKeyStorePath(String sslClientKeyStorePath); ConfigBuilder sslClientTrustCertificates(List<String> sslClientTrustCertificates); ConfigBuilder sslClientTrustStorePath(String sslClientTrustStorePath); ConfigBuilder sslClientKeyStorePassword(char[] sslClientKeyStorePassword); ConfigBuilder sslServerTlsKeyPath(String sslServerTlsKeyPath); ConfigBuilder sslServerTlsCertificatePath(String sslServerTlsCertificatePath); ConfigBuilder sslClientTlsKeyPath(String sslClientTlsKeyPath); ConfigBuilder sslClientTlsCertificatePath(String sslClientTlsCertificatePath); ConfigBuilder keyData(KeyConfiguration keyData); ConfigBuilder useWhiteList(boolean useWhiteList); ConfigBuilder workdir(String workDir); Config build();  }### Answer:
@Test public void nullIsNullAndNotAStringWithTheValueOfNull() { assertThat(ConfigBuilder.toPath(null, null)).isNull(); assertThat(ConfigBuilder.toPath(null, "test")).isNotNull(); }