private String getDefaultValue(String parameterName, PageableDefault pageableDefault, String defaultSchemaVal) {
		String defaultValue = null;
		switch (parameterName) {
			case "size":
				if (pageableDefault != null) {
					// "size" is aliased as "value"
					int size = pageableDefault.size();
					Object defaultSize;
					try {
						defaultSize = PageableDefault.class.getMethod("size").getDefaultValue();
					}
					catch (NoSuchMethodException e) {
						LOGGER.warn(e.getMessage());
						defaultSize = null;
					}
					if (Objects.deepEquals(size, defaultSize)) {
						size = pageableDefault.value();
					}
					defaultValue = String.valueOf(size);
				}
				else if (isRepositoryRestConfigurationPresent())
					defaultValue = String.valueOf(optionalRepositoryRestConfigurationProvider.get().getRepositoryRestConfiguration().getDefaultPageSize());
				else if (isSpringDataWebPropertiesPresent())
					defaultValue = String.valueOf(optionalSpringDataWebPropertiesProvider.get().getSpringDataWebProperties().getPageable().getDefaultPageSize());
				else
					defaultValue = defaultSchemaVal;
				break;
			case "page":
				if (pageableDefault != null) {
					if (isSpringDataWebPropertiesPresent() && optionalSpringDataWebPropertiesProvider.get().getSpringDataWebProperties().getPageable().isOneIndexedParameters()) {
						defaultValue = String.valueOf(pageableDefault.page() + 1);
					}
					else {
						defaultValue = String.valueOf(pageableDefault.page());
					}
				}
				else if (isSpringDataWebPropertiesPresent() && optionalSpringDataWebPropertiesProvider.get().getSpringDataWebProperties().getPageable().isOneIndexedParameters())
					defaultValue = "1";
				else
					defaultValue = defaultSchemaVal;
				break;
			default:
				// Do nothing here
				break;
		}
		return defaultValue;
	}
Gets default value.

@param parameterName    the parameter name
@param pageableDefault  the pageable default
@param defaultSchemaVal the default schema val
@return the default value
springdoc-openapi-starter-common/src/main/java/org/springdoc/core/customizers/DataRestDelegatingMethodParameterCustomizer.java