In case of code generation via swagger-codegen-maven-plugin there are problems with escaping some quote symbols in the sources generated. This causes compilation errors.
The following plugin settings are used for repro:

    <build>
        <plugins>
            <plugin>
                <groupId>io.swagger.codegen.v3</groupId>
                <artifactId>swagger-codegen-maven-plugin</artifactId>
                <version>3.0.41</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/../ewm-main-service-spec.json</inputSpec>
                            <language>spring</language>
                            <library>spring-boot</library>
                            <apiPackage>${apiPackage}</apiPackage>
                            <modelPackage>${modelPackage}</modelPackage>
                            <configOptions>
                                <sourceFolder>src/main/java/</sourceFolder>
                                <dateLibrary>java8</dateLibrary>
                                <interfaceOnly>true</interfaceOnly>
                                <useBeanValidation>true</useBeanValidation>
                                <performBeanValidation>true</performBeanValidation>
                            </configOptions>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

See the whole demo pom.xml in terekhovmv/java-explore-with-me-fixes@da018e0 .

This issue is not reproduced for specs of stats service.

Prerequisite: It is highly recommended to merge yandex-praktikum/java-explore-with-me#22 changes, since generation via swagger-codegen-maven-plugin does not work correctly for original ewm-main-service-spec.json file.

In case of code generation via swagger-codegen-maven-plugin there are several problems with operationIds provided in ewm-main-service-spec.json file (see demo pom.xml in terekhovmv/java-explore-with-me-fixes@da018e0).

1. Some of operationIds contain numeric suffixes, and this suffixes appear in methods of generated *Api interfaces (getEvents_2, getEvent_1). Solution: remove suffixes at least.
2. There is no consistency in naming (delete / deleteCompilation, registerUser / addEvent / saveCompilation). Solution: provide consistent naming.
3. Since *Api interfaces are generated for top level endpoint components (/users/* => UsersApi) there are problems with identifying endpoint methods for different roles (e.g. cancelRequest and changeRequestStatus in the UsersApi interface). Solution: put the role as prefix in operationIds.
4. Since operationIds must be unique among all operations described in your API (see https://swagger.io/docs/specification/paths-and-operations/), we should provide enough global descriptive names (delete or getEvent_1 does not work).

Tabular view of changes proposed in this PR: