http://www.dropwizard.io/2.0.18/dropwizard-bom/dropwizard-dependencies/dropwizard-parent/dropwizard-configuration: Dropwizard is a Java framework for developing ops-friendly, high-performance, RESTful web applications.
  • Coda Hale
  • Nick Telford
  • Graham O'Regan
  • Ryan Kennedy
  • Camille Fournier
  • Carlo Barbara
  • Matt Veitas
  • Ryan Tenney
  • Jochen Schalanda
  • Glenn McAllister
  • Nick Babcock
  • Justin Plock
  • Artem Prigoda 
public class io.dropwizard.configuration.EnvironmentVariableLookup implements org.apache.commons.text.lookup.StringLookup
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: io.dropwizard.configuration.EnvironmentVariableLookup
  super_class: java.lang.Object
{
  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // io.dropwizard.configuration.EnvironmentVariableLookup this
         0: .line 8
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // io.dropwizard.configuration.EnvironmentVariableLookup this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/dropwizard/configuration/EnvironmentVariableLookup;

  public java.lang.String lookup(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=2, args_size=2
        start local 0 // io.dropwizard.configuration.EnvironmentVariableLookup this
        start local 1 // java.lang.String key
         0: .line 14
            aload 1 /* key */
            invokestatic java.lang.System.getenv:(Ljava/lang/String;)Ljava/lang/String;
            areturn
        end local 1 // java.lang.String key
        end local 0 // io.dropwizard.configuration.EnvironmentVariableLookup this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/dropwizard/configuration/EnvironmentVariableLookup;
            0    1     1   key  Ljava/lang/String;
    MethodParameters:
      Name  Flags
      key   
}
SourceFile: "EnvironmentVariableLookup.java"