@Override
	public boolean equals(Object o) {
		if (this == o) return true;
		if (o == null || getClass() != o.getClass()) return false;
		ParameterId that = (ParameterId) o;
		if (this.pName == null && StringUtils.isBlank(this.paramType))
			return Objects.equals($ref, that.$ref);
		if (this.pName != null && StringUtils.isBlank(this.paramType))
			return Objects.equals(pName, that.pName);

		return Objects.equals(pName, that.pName) && Objects.equals(paramType, that.paramType);

	}
Set ref.

@param $ref the ref
springdoc-openapi-starter-common/src/main/java/org/springdoc/core/models/ParameterId.java