Wrong Query parameter serialization when using Object

Description

We are using objects in query parameters for a get operations, when we call the service, object parameters are not serialized as expected.
The toString method is call and le url is corrupted

/v1/declarations/etablissements?page=class%20PageInType%20%7B%0A%20%20%20%20page%3A%2010%0A%20%20%20%20size%3A%2050%0A%7D&filtre=class%20FiltreRechercherEtablissementDSNType%20%7B%0A%20%20%20%20siret%3A%20null%0A%20%20%20%20siren%3A%20808332670%0A%20%20%20%20annee%3A%202017%0A%20%20%20%20mois%3A%2001%0A%20%20%20%20localite%3A%20null%0A%20%20%20%20effectifCalculeDebutDePeriode%3A%20null%0A%20%20%20%20effectifCalculeFinDePeriode%3A%20null%0A%20%20%20%20denomination%3A%20null%0A%20%20%20%20codeNAF%3A%20null%0A%7D&tri=class%20TriRechercherEtablissementsDSNType%20%7B%0A%20%20%20%20siret%3A%20null%0A%20%20%20%20siren%3A%20desc%0A%20%20%20%20mois%3A%20null%0A%20%20%20%20localite%3A%20null%0A%20%20%20%20effectifCalculeFinDePeriode%3A%20null%0A%20%20%20%20effectifCalculeDebutDePeriode%3A%20null%0A%20%20%20%20denomination%3A%20null%0A%20%20%20%20codeNAF%3A%20null%0A%20%20%20%20annee%3A%20null%0A%7D

Swagger-codegen version

3.0.0-SNAPSHOT

Swagger declaration file content or url

tags:
- declarations
parameters:
- name: page
in: query
required: false
style: form
schema:
$ref: '#/components/schemas/PageIn_Type'
- name: filtre
in: query
required: false
style: form
schema:
$ref: '#/components/schemas/FiltreRechercherEtablissementDSN_Type'
- name: tri
in: query
required: false
style: form
explode: false
schema:
$ref: '#/components/schemas/TriRechercherEtablissementsDSN_Type'
responses:
...

PageIn_Type:
  type: object
  properties:
    page:
      type: number
    size:
      type: number

...
FiltreRechercherEtablissementDSN_Type:
type: object
properties:
siret:
type: string
siren:
type: string
annee:
type: string
mois:
type: string
localite:
type: string
effectifCalculeDebutDePeriode:
type: string
effectifCalculeFinDePeriode:
type: string
denomination:
type: string
codeNAF:
type: string

Command line used for generation

 		<plugin>
			<groupId>io.swagger</groupId>
			<artifactId>swagger-codegen-maven-plugin</artifactId>
			<version>${swagger-codegen-version}</version>
			<executions>
				<execution>
					<id>generate-client</id>
					<goals>
						<goal>generate</goal>
					</goals>
					<phase>generate-sources</phase>
					<configuration>
						<inputSpec>${project.basedir}/src/main/resources/dsnci_ws_consultation_be_v1.0.yaml</inputSpec>
						<language>java</language>
						<apiPackage>fr.recouv.dsn.ws.rest.api.v1</apiPackage>
						<modelPackage>fr.recouv.dsn.ws.rest.dto.v1</modelPackage>
						<output>${generated-swagger-path}</output>
						<withXml>true</withXml>
						<generateApis>true</generateApis>
						<generateApiTests>true</generateApiTests>
					</configuration>
				</execution>
			</executions>
		</plugin>

Start with the generated Java client and the swagger-codegen Maven execution shown in the report, using the supplied OpenAPI schema as the reproduction input. Trace query-parameter serialization for the object parameters page, filtre, and tri, then add a regression check for the generated request URL. Done means object properties are serialized according to the declared query style rather than via toString.