t.Error(err)
	}

	lvl := &Level3{}
	if err := DB.Save(lvl).Error; err != nil {
		t.Error(err)
	}

	sublvl1 := &Level4{Level3ID: lvl.ID}
	if err := DB.Save(sublvl1).Error; err != nil {
		t.Error(err)
	}
	sublvl2 := &Level4{Level3ID: lvl.ID}
	if err := DB.Save(sublvl2).Error; err != nil {
		t.Error(err)
	}

	lvl.Level4s = []*Level4{sublvl1, sublvl2}

      .isEqualTo(date("1950-01-01T00:00:00.000+0000").time)
    assertThat(Adapters.parseUtcTime("500101010000Z"))
      .isEqualTo(date("1950-01-01T01:00:00.000+0000").time)

    assertThat(Adapters.parseUtcTime("491231225959Z"))
      .isEqualTo(date("2049-12-31T22:59:59.000+0000").time)
    assertThat(Adapters.parseUtcTime("491231235959Z"))
      .isEqualTo(date("2049-12-31T23:59:59.000+0000").time)
  }

* It should probably have a declaration of the body it should receive, e.g. `body: InvoiceEvent`.
* And it could also have a declaration of the response it should return, e.g. `response_model=InvoiceEventReceived`.

{* ../../docs_src/openapi_callbacks/tutorial001.py hl[16:18,21:22,28:32] *}

There are 2 main differences from a normal *path operation*:

import java.util.Date;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.convert.StringConversionUtil;
import org.codelibs.core.convert.TimestampConversionUtil;

/**
 * Converter for timestamps.
 *
 * @author higa
 */
public class TimestampConverter implements Converter {

    /**
     * The pattern for the date and time.
     */
    protected String pattern;

        Date testValue = new Date();
        OptionalEntity<Date> result = OptionalUtil.ofNullable(testValue);

        assertNotNull(result);
        assertTrue(result.isPresent());
        assertEquals(testValue, result.get());
    }

    public void test_ofNullable_withNullDate() {
        Date testValue = null;
        OptionalEntity<Date> result = OptionalUtil.ofNullable(testValue);

import java.util.Date;

import org.codelibs.core.beans.Converter;
import org.codelibs.core.convert.DateConversionUtil;
import org.codelibs.core.convert.StringConversionUtil;
import org.codelibs.core.lang.StringUtil;

/**
 * Converter for SQL dates.
 *
 * @author higa
 */
public class SqlDateConverter implements Converter {

    /**
     * The date pattern.
     */

{* ../../docs_src/dependencies/tutorial008_an_py39.py hl[18:19,26:27] *}

The same way, you could have some dependencies with `yield` and some other dependencies with `return`, and have some of those depend on some of the others.

And you could have a single dependency that requires several other dependencies with `yield`, etc.

You can have any combinations of dependencies that you want.

        this.executionProperties = executionProperties;
        return this;
    }

    @Override
    public Date getBuildStartTime() {
        return buildStartTime;
    }

    @Override
    public ProjectBuilderConfiguration setBuildStartTime(Date buildStartTime) {
        this.buildStartTime = buildStartTime;
        return this;
    }

# Extra Models { #extra-models }

Continuing with the previous example, it will be common to have more than one related model.

This is especially the case for user models, because:

* The **input model** needs to be able to have a password.
* The **output model** should not have a password.
* The **database model** would probably need to have a hashed password.

/// danger

        assertEquals(32, derived1.length, "Derived key should have correct length");
        assertEquals(32, derived2.length, "Derived key should have correct length");
        assertEquals(32, derived3.length, "Derived key should have correct length");

        assertFalse(Arrays.equals(derived1, derived2), "Different labels should produce different keys");