Fixes to allow gson to correctly serialise constants and enums

[eamansour]

Why?

Related to findings as part of galasa-dev/projectmanagement#1467

Currently, generated Java bean classes declare constants as static fields, but gson doesn't serialise static fields, so the resulting JSON doesn't include these constants.

When converting an enum value to JSON, it doesn't use the enum's human-readable string values and instead, uses the enum's constant value as it is declared.

Changes

• Changed declaration of constants to non-static fields (i.e. public final String MY_CONSTANT = "ConstantValue") so that gson can serialise such fields
• Added @SerializedName annotations to generated enum values so that enums are correctly serialised into their string representations
  • For example, given an enum value USERNAME_PASSWORD("UsernamePassword") converting this value to JSON will be rendered as UsernamePassword instead of USERNAME_PASSWORD
• Removed space in generated constructors (e.g. public MyBean () now becomes public MyBean())
• Removed space after enum values (e.g. MY_VALUE ("MyValue") now becomes MY_VALUE("MyValue"))

[aashir21]

👍🏻