Slava Semushin

- unique constraint naming: `uc__` - foreign constraint naming: `fk__` - always specify `uniqueConstraintName` attribute when `unique="true"` is used to set a predictable name for the constraint

`modifyDataType` mustn't be used with NOT NULL fields as it loses this property (see #1266)

It has [turned out](https://travis-ci.org/github/php-coder/mystamps/jobs/661263695) that `columnDataType is required for addNotNullConstraint on mysql`

> Yet another one: each must have context attribute with supported values. Liquibase 4.5.0 has introduced quality checks and at least it has a rule to ensure that every changeset...

It has [turned out](https://app.travis-ci.com/github/php-coder/mystamps/jobs/544834367) that `columnDataType is required for setColumnRemarks on mysql`

`renameColumn` also loses `NOT NULL` on MySQL. See for example: https://github.com/php-coder/mystamps/pull/1652/files#diff-ed5ff70f6771c05d79956c1adea7b7a53123b9163fa10bfdc85a9efb27e0f561

Despite I removed the original comment in 6af463b3cd5079e14f0883b94e096ba420331822 commit, the issue is still relevant can has to be fixed.

From https://github.com/spring-projects/spring-framework/wiki/Spring-Framework-Versions: > Please upgrade to Spring Framework 5.1+ (and the corresponding Spring Boot 2.1+) for JDK 11+ support So, we first should update Spring Boot to 2.1.x: #1161

It seems like Groovy-related stuff requires some additional work in order to work with JDK11 (https://travis-ci.com/github/php-coder/mystamps/jobs/464914094): 1. Unit tests fail to compile: > [ERROR] Failed to execute goal org.codehaus.gmavenplus:gmavenplus-plugin:1.5:testCompile (default)...

Notes to myself: - JFR (Java Flight Recorder) + JMC (Java Mission Control) - String compaction - AppCDS (Application Class Data Sharing)