Avoid error when doc path has spaces and server is relative

Author: ind1go

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/OpenAPIDeserializer.java

@@ -701,10 +701,14 @@ public Server getServer(ObjectNode obj, String location, ParseResult result, Str
 						value = absURI.resolve(new URI(value)).toString();
 					}
 				} catch (URISyntaxException e) {
-					String variable = value.substring(value.indexOf("{") + 1, value.indexOf("}"));
-					if (server.getVariables() != null) {
-						if (!server.getVariables().containsKey(variable)) {
-							result.warning(location, "invalid url : " + value);
+					final int openBrace = value.indexOf("{");
+					final int closeBrace = value.indexOf("}");
+					if (openBrace > -1 && closeBrace > -1) {
+						String variable = value.substring(openBrace + 1, closeBrace);
+						if (server.getVariables() != null) {
+							if (!server.getVariables().containsKey(variable)) {
+								result.warning(location, "invalid url : " + value);
+							}
 						}
 					}
 				}