TimestampsTest osa being awesome

TimestampsTest.java

import org.junit.Test;
import org.reflections.Reflections;

import javax.persistence.Entity;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

public class TimestampsTest {

    @Test
    public void allRepositoriesHaveCreatedAndUpdatedTimestamps() {
        Reflections reflections = new Reflections("com.myapp");
        Set<Class<?>> classes = reflections.getTypesAnnotatedWith(Entity.class);
        validateMethodsExists(classes);
        validateAnnotationExists(classes);
    }

    private void validateAnnotationExists(Set<Class<?>> classes) {
        for (Class<?> aClass : classes) {
            List<Method> collect = Arrays.stream(aClass.getDeclaredMethods())
                    .filter(method -> Arrays.stream(method.getAnnotations())
                            .filter(annotation ->
                                    annotation.toString().equalsIgnoreCase("@javax.persistence.PrePersist()") ||
                                            annotation.toString().equalsIgnoreCase("@javax.persistence.PreUpdate()"))
                            .count() > 0)
                    .collect(Collectors.toList());
            String errorMessage = generateErrorMessage(aClass);
            assertThat(errorMessage, collect.size(), is(2));
        }
    }

    private void validateMethodsExists(Set<Class<?>> classes) {
        for (Class<?> clazz : classes) {
            List<Method> collect = Arrays.stream(clazz.getDeclaredMethods())
                    .filter(method -> method.getName().equals("getCreatedAt") || method.getName().equals("getUpdatedAt"))
                    .collect(Collectors.toList());
            String errorMessage = generateErrorMessage(clazz);
            assertThat(errorMessage, collect.size(), is(2));
        }
    }

    private String generateErrorMessage(Class<?> aClass) {
        StringBuilder sb = new StringBuilder();
        String tab = "\n\t";
        sb.append("\n\n")
                .append("Every @Entity class must have a createdAt and UpdatedAt timestamp for auditing purposes")
                .append("and must have annotations:")
                .append("\n")
                .append(tab + "1. @javax.persistence.PrePersist()")
                .append(tab + "2. @javax.persistence.PreUpdate()")
                .append("\n\n")
                .append("Class: ").append(aClass.getName()).append(" does not comply aforementioned rule")
                .append("\n\n");

        return sb.toString();
    }
}