[From string (line 29) ]                                                                                                    
                                                                                                                            
@startuml                                                                                                                   
                                                                                                                            
                                                                                                                            
                                                                                                                            
skinparam backgroundColor transparent                                                                                       
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... ( skipping 2207 lines )                                                                                                 
...                                                                                                                         
participant c2 <<component>>  [                                                                                             
== Sign In Controller                                                                                                       
//<size:12>[Spring MVC Rest Controller]</size>//                                                                            
]                                                                                                                           
                                                                                                                            
participant c3 <<component>>  [                                                                                             
== Security Component                                                                                                       
//<size:12>[Spring Bean]</size>//                                                                                           
]                                                                                                                           
                                                                                                                            
participant c4 <<container>>  [                                                                                             
== Database                                                                                                                 
//<size:12>[Relational Database Schema]</size>//                                                                            
]                                                                                                                           
                                                                                                                            
c1 -> c2 : **[[https://github.com/plantuml-stdlib/C4-PlantUML <$robot2,scale=0.25> Submits credentials to]]**\n//<size:1 ...
c2 -> c3 : **Calls isAuthenticated() on**                                                                                   
c3 -> c4 : **select * from users where username = ?**\n//<size:12>[JDBC]</size>//                                           
                                                                                                                            
RelIndex(4a, c3, c4, "a parallel call")                                                                                     
^^^^^                                                                                                                       
 Syntax Error?