import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "Customers")
public class Customer {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Long id;
	private String firstName;
	private String lastName;
	@Column(name = "email")
	private String emailAddress;

	public Long getId() {
		return id;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	public String getEmailAddress() {
		return emailAddress;
	}

	public void setEmailAddress(String emailAddress) {
		this.emailAddress = emailAddress;
	}

}

CREATE TABLE `customers` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `first_name` varchar(255) DEFAULT NULL,
  `last_name` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=latin1;

hibernate.physical_naming_strategy = xxx.naming_strategy.CustomPhysicalNamingStrategy
hibernate.hbm2ddl.auto = none

import org.hibernate.boot.model.naming.Identifier;
import org.hibernate.boot.model.naming.PhysicalNamingStrategy;
import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;

public class CustomPhysicalNamingStrategy implements PhysicalNamingStrategy {

	@Override
	public Identifier toPhysicalCatalogName(final Identifier identifier, final JdbcEnvironment jdbcEnv) {
		return convertToSnakeCase(identifier);
	}

	@Override
	public Identifier toPhysicalColumnName(final Identifier identifier, final JdbcEnvironment jdbcEnv) {
		return convertToSnakeCase(identifier);
	}

	@Override
	public Identifier toPhysicalSchemaName(final Identifier identifier, final JdbcEnvironment jdbcEnv) {
		return convertToSnakeCase(identifier);
	}

	@Override
	public Identifier toPhysicalSequenceName(final Identifier identifier, final JdbcEnvironment jdbcEnv) {
		return convertToSnakeCase(identifier);
	}

	@Override
	public Identifier toPhysicalTableName(final Identifier identifier, final JdbcEnvironment jdbcEnv) {
		return convertToSnakeCase(identifier);
	}

	private Identifier convertToSnakeCase(final Identifier identifier) {
		if (identifier != null) {
			final String regex = "([a-z])([A-Z])";
			final String replacement = "$1_$2";
			final String newName = identifier.getText().replaceAll(regex, replacement).toLowerCase();

			return Identifier.toIdentifier(newName);
		} else {
			return null;
		}
	}
}

		doInJPA(entityManager -> {

			Customer customer = new Customer();
			customer.setEmailAddress("Some@mail.com");
			customer.setFirstName("FirstName");
			customer.setLastName("LastName");

			entityManager.persist(customer);

		});

Hibernate: alter table Customers add column firstName varchar(255)
Hibernate: alter table Customers add column lastName varchar(255)

Hibernate: insert into customers (email, first_name, last_name) values (?, ?, ?)