JWT Auth Builders.java

    authBuilder
        .verifiesClaimsBy(
            c -> firebaseApplicationName.equals(c.getAudience())
        )
        .verifiesClaimsBy(
            c -> (ISSUER_PREFIX + firebaseApplicationName).equals(c.getIssuer())
        )
        .verifiesClaimsBy(
            c -> {
              // we may not need this once we have our own signin provider proxied by Firebase
              String email = c.getStringClaim(CLAIM_EMAIL);
              if (email == null) return false;
              return email.endsWith("@infusionsoft.com");
            }
        )
        .verifiesClaimsBy(
            c -> c.getBooleanClaim(CLAIM_EMAIL_VERIFIED)
        )
        .verifiesClaimsBy(
            c -> {
              final String firebaseClaimString = c.getStringClaim(CLAIM_FIREBASE);
              if (firebaseClaimString == null) return false;
              final Map<String, Object> firebaseClaims = new Gson().fromJson(firebaseClaimString, HashMap.class);
              final Object signinProvider = firebaseClaims.get(CLAIM_FIREBASE_SIGN_IN_PROVIDER);
              return GOOGLE_SIGNIN_PROVIDER.equals(signinProvider);
            }
        )
    ;

// OR do we prefer:

    authBuilder
        .verifiesClaimsBy(
            c -> firebaseApplicationName.equals(c.getAudience())
            , c -> (ISSUER_PREFIX + firebaseApplicationName).equals(c.getIssuer())
            , c -> {
              // we may not need this once we have our own signin provider proxied by Firebase
              String email = c.getStringClaim(CLAIM_EMAIL);
              if (email == null) return false;
              return email.endsWith("@infusionsoft.com");
            }
            , c -> c.getBooleanClaim(CLAIM_EMAIL_VERIFIED)
            , c -> {
              final String firebaseClaimString = c.getStringClaim(CLAIM_FIREBASE);
              if (firebaseClaimString == null) return false;
              final Map<String, Object> firebaseClaims = new Gson().fromJson(firebaseClaimString, HashMap.class);
              final Object signinProvider = firebaseClaims.get(CLAIM_FIREBASE_SIGN_IN_PROVIDER);
              return GOOGLE_SIGNIN_PROVIDER.equals(signinProvider);
            }
        )
    ;

what is c?

also can i do this without lambdas?